HvrauutJVtt 


•• 


PRINCIPLES 


OF 


PLANT  CULTURE 


AN   ELEMENTARY   TREATISE   DESIGNED  AS  A 
TEXT-BOOK  FOR  BEGINNERS  IN  AGRI- 
CULTURE AND   HORTICULTURE 


BY 

E.    S.    GOFF 

\\ 

PROFESSOR  OF  HORTICULTURE  IN  THE  UNIVERSITY  OF  WISCONSIN 


SECOND   EDITION,  REVISED 


PUBLISHED  BY  THE  AUTHOR 
1899 


COPYRIGHT,  1897 
BY   E.   S.    GOFF 


M.  J.  CANTWEL.L,  Printer 
Madison,  Wis. 


PREFACE 


This  book  has  grown  out  of  the  author' s  experience  in 
the  lecture  room  and  laboratory,  while  giving  instruction 
to  students  in  the  Short  Course  in  Agriculture,  in  the 
University  of  Wisconsin. 

It  is  intended  especially  for  students  who  have  had 
little  or  no  previous  instruction  in  botany,  and  it  is  hoped 
that  it  may  also  be  found  interesting  and  profitable  to  the 
general  reader  who  would  learn  more  of  the  principles 
that  underlie  the  culture  of  plants. 

It  is  expected  that  the  instructor  will  amplify  the  text 
in  proportion  to  the  time  at  his  command,  and  the  ca- 
pacity of  his  students.  In  the  a^&brjs^abtice,  the  first 
three  chapters  have  been  found  sufficient  for  a  term  of 
twelve  weeks,  and  the  remaining  chapters,  supplemented 
with  some  special  work  in  horticulture,  have  served  for 
a  second  term. 

A  syllabus  of  laboratory  work  is  added  as  an  appendix. 

It  is  hoped  that  this  book  may  prove  as  useful  to  other 
instructors  as  it  has  proved  to  the  author  during  its  evo- 
lution. 

Madison,  Wis.,  Feb.  15,  1897.  E.  S.  GOFF. 

• 

NOTE.— In  the  second  edition  (1899)  a  number  of  verbal 
changes  have  been  made  and  a  few  additional  paragraphs  and 
illustrations  have  been  inserted. 


4 9 85 5 U 


ACKNOWLEDGEMENTS 


The  author  desires  feo  express  his  thanks  to  Prof. 
Charles  E.  Barnes,  of  the  University  of  Chicago,  Prof. 
F.  W.  Woll,  of  the  Wisconsin  Agricultural  Experiment 
Station  and  Mr.  F.  Cranefield,  the  author's  assistant  in 
horticulture,  for  revision  of  the  manuscript  (of  the  first 
edition),  and  for  many  valuable  suggestions. 

Figures  14,  15,  18,  19,  20,  21,  22,  28,  29,  30,  34,  46,  47, 
48,  49,  53,  54,  55  and  83  were  copied  from  "Agricultural 
Botany, "  with  the  sanction  of  the  author,  Prof.  M.  C. 
Potter,  of  the  Durham  College  of  Science,  England. 
Figures  61,  62,  63,  82,  84,  94,  98,  100,  101,  102,  103,  113, 
117,  118,  119,  120,  121,  123  and  128  are  from  "The  Nur- 
sery Book,"  by  Prof.  L.  H.  Bailey,  and  are  used  by  per- 
mission. Figures  31,  59,  81,  85,  99  and  130  are  from 
"The  Amateur  Fruit  Book/'  by  Prof.  S.  B.  Green,  and 
are  used  by  permission.  Figure  32  is  from  a  photograph 
kindly  loaned  by  Prof.  Green.  Figures  37,  39,  40,  41, 
42  and  44  are  copied  by  permission  of  the  publishers 
from  "Barry's  Fruit  Garden."  Figures  94  and  95  are 
from  "How  to  Make  the  Garden  Pay,'-  by  T.  Greiner, 
and  are  used  by  permission.  Figures  65  and  66  were 
copied  by  permission  from  Bulletin  No.  37,  of  the  Ehode 
Island  Agricultural  Experiment  Station.  Figures  77,  78 
and  79  are  from  cuts  in  the  possession  of  the  Wisconsin 
Agricultural  Experiment  Station. 


CONTENTS 


PAGE. 

Chapter    I. —  Introductory 9 —  21 

Chapter  II.— The  Round  of  Plant  Life 22—114 

Section    1— The  Behavior  of  Seeds  toward  Water    22—  24 

"          2— Germination 24—  32 

"          3— The  Plantlet 32—48 

4— The  Inner  Structure  of  the  Plantlet...    48—  56 
"         5— The  Water  of  Plants  and  its  Move- 
ments      57 —  64 

"          6— The  Root  and  the  Soil 64—  77 

"          7— The  Stem „ 78—  80 

"          8— The  Leaves 81—  84 

"          9— The  Buds 84—  93 

"        10— The  Flower 93—101 

"        11— The  Fruit  and  the  Seed 101—104 

12— The  Gathering  and  Storing  of  Seeds..  104—109 
"        13— The  Decline  of  Growth  and  the  Rest 

Period 109—114 

Chapter  III.— The  Plant  as  Affected  by  Unfavorable 

Environment 115 — 180 

Section  1— The  Plant  as  Affected  by  Unfavorable 

Temperature 115—132 

A— By  Excessive  Heat 115—118 

B— By  Excessive  Cold 118—124 

Section  2— Methods  of  Averting  Injury  by  Cold..  124—132 
A— During  the  Dormant  Period  124—126 
B— During  the  Growing  Period  126—122 
Section  3—  The  Plant  as  Affected  by  Unfavorable 

Water  Supply 133—140 

A— By  Excessive  Water 133—137 

B— By  Insufficient  Water 137—140 


8  Contents. 

Chapter  III.—  Section  4.—  The  Plant  as  Affected  by    PAGE. 

Unfavorable  Light 140—144 

A— By  Excessive  Light 140—142 

B— By  Insufficient  Light 142—144 

Section  5— The  Plant  as  Affected  by  Unfavorable 

Wind 144—145 

A— By  Excessive  Wind 144 

B— By  Insufficient  Wind 145 

Section  6— The  Plant  as  Affected  by  Unfavorable 

Food  Supply 146—153 

A— By  Excessive  Food 146—147 

B— By  Insufficient  Food 149—153 

Section  7— The  Plant  as  Affected  by  Parasites 153—178 

A — By  Animal  Parasites 154 — 170 

B— By  Vegetable  Parasites 170—178 

Section  8— The  Plant  as  Affected  by  Weeds 178—180 

Chapter  IV. —  Plant  Manipulation 181 — 257 

Section  1— Plant  Propagation 181—225 

A— By  Seeds 182—183 

B — By  Division,  i.  e.,  by  parts 

other  than  Seeds 183—225 

Section  2— Transplanting 225—241 

A— Lifting  the  Plant 227—229 

B— Removing  the  Plant 229—231 

C— Replanting 231—239 

D— After  Care  of  Transplanted 

Stock 239—241 

Section  3— Pruning 242—2-58 

A — Formative  Pruning 245 — 251 

B— Stimulative  Pruning 251—254 

C— Protective  Pruning 254— 255 

D — Maturative  Pruning 255 

Chapter  V.— Plant  Breeding 259—268 


PRINCIPLES  OF  PLANT  CULTURE 


CHAPTER  I 
INTRODUCTORY 

Before  taking  up  a  systematic  study  of  plant  culture, 
we  may  profitably  consider  a  few  principles  of  a  more 
general  nature. 

1.  Close  Observation  offers  the  best  means  of  gaining 
knowledge  of  material  things.     The  habit  of  accurate 
discernment,  and  of  studying  the  relations  of  and  the 
reasons  for  things  and  facts  as  we  find  them,  should  be 
constantly  cultivated.     Knowledge  once  gained  must  be 
applied  in  the  proper  place,  the  proper  manner  and  at 
the  proper  time,  or  the  highest  success  in  any  calling 
cannot  be  expected. 

2.  The  Difference   between   Art  and  Science.     Art  is 
simply  knowing  how  to  do  a  thing  without  reference  to 
reasons.     Science  considers  the  reasons  for  doing  it  in  a 
particular  manner.     Art  implies  more   or  less  of  skill 
gained  through  practice.     Science  implies  a  knowledge 
of  the  objects  to  be  gained  by  a  given  operation  and  the 
conditions  affecting  the  process. 

An  intelligent  but  ignorant  person  might  be  taught  to 
prepare  and  insert  a  cion  (386)*  in  the  most  approved 

*The  numbers  in  parenthesis  in  the  text  refer  to  the  numbered  para- 
graphs in  this  book,  and  are  intended  to  help  students  to  a  better  under- 
standing of  the  subject.  Students  should  be  urged  to  look  up  these  cross 
references. 


10  Principles  of  Plant  Culture. 

manner.  This  pertains  to  the  art  of  grafting.  The  same 
person  might  be  taught  the  reasons  ivliy  each  step  of  the 
process  is  performed  in  its  particular  manner.  This 
pertains  to  the  science  of  grafting.  One  may  become  a 
skilled  grafter  without  learning  the  science  of  grafting, 
but  he  cannot  graft  intelligently.  The  artisan,  however 
skillful,  who  knows  only  the  art,  cannot  become  a  master 
workman  in  the  highest  sense  until  he  learns  also  the 
science  that  underlies  his  trade. 

The  art  of  doing  any  kind  of  work  is  best  learned  by 
working  under  the  guidance  of  a  skilled  workman.  The 
science  is  best  learned  from  books  with  the  help  of  trained 
instructors.  Science  not  yet  wrought  out,  and  hence  not 
explained  in  publications,  is  learned  by  close,  persistent 
and  thoughtful  observation  and  study. 

3.  Environment  is  a  term  used  to  express  all  the  out- 
side influences,  taken  as  a  whole,  that  aifect  a  given 
object  in  any  way.     A  plant  or  animal,  for  example,  is 
affected  by  various  external  conditions,  as  heat,  moisture, 
light,  food  etc.     These  conditions  and  all  others  that  in- 
fluence the  plant  or  animal  make  up  its  environment. 

4.  What  is  Culture?     The   well-being   of    a   plant   or 
animal  depends  very  much  upon  a  favorable  condition  of 
environment,  and  with  the  proper  knowledge,  we  can  do 
much  toward  keeping  the  environment  in  a  favorable 
condition.     For  example,  if  the  soil  in  which  a  plant  is 
rooted  lacks  plant  food,   we  can  enrich  it;   if  it  lacks 
sufficient  moisture,  we  can  dampen  it;    if  the  plant  is 
shaded  by  weeds,  we  can  remove  them.     These,  and  any 
other  things  that  we  can  do  to  make  the  environment 
more  favorable,  constitute  culture  in  the  broadest  sense 


Introductory.  11 

of  the  term.  A  full  knowledge  of  the  culture  of  any 
plant  implies  a  knowledge,  not  only  of  the  plant  and  its 
needs,  but  of  each  separate  factor  in  its  environment, 
and  how  to  maintain  this  factor  in  the  condition  that 
best  favors  the  plant's  development  toward  some  special 
end,  as  the  production  of  the  finest  and  highest  type 
of  fruit,  flowers  or  seed.  We  should  know,  not  only 
the  soil  that  best  suits  the  plant,  but  the  amount  of 
light,  moisture,  warmth  and  food  in  which  it  prospers 
best.  We  should  know  the  enemies  that  prey  upon  it, 
the  manner  in  which  they  work  their  harm,  and  how  to 
prevent  their  ravages.  We  should  know,  in  short,  how 
to  regulate  every  factor  of  environment  so  as  to  promote 
the  plant's  well-being  to  the  utmost,  as  well  as  how  to 
develop  every  desirable  quality  the  plant  possesses. 

5.  Domestic  or  Domesticated  Plants  or  Animals  are  those 
that  are  in  the  state   of  culture.     In   nature,  different 
plants  and  animals  struggle  with  one  another  for  space 
and  food.     Only  those  best  adapted  to  their  environment 
survive,  and  these  are  often  much  restricted  in  their  de- 
velopment.   In  culture,  the  intelligence  and  the  energy  of 
man  produce  a  more  favorable  environment  for  the  species 
he  desires  to  rear;   hence  domestic  plants  and  animals 
attain  higher  development  in  certain  directions  than  their 
wild  parents.    The  cultivated  potato,  for  example,  grows 
larger,  is  more  productive  and  is  higher  in  food  value 
than  the  wild  potato.     The  finer  breeds  of  horses  and 
cattle  are  superior  to  their  wild  progenitors  in  usefulness 
to  man. 

6.  Culture   Aims  to  Improve    Nature's    Methods   rather 
than  to  imitate  them.     By  cutting  out  the  superfluous 


12  Principles  of  Plant  Culture. 

branches  from  a  fruit  tree,  we  enable  the  fruit  on  the  re- 
maining branches  to  reach  a  higher  state  of  development. 
By  planting  corn  at  the  proper  distances,  we  prevent 
crowding  and  enable  each  plant  to  attain  its  maximum 
growth.  We  should  constantly  study  nature's  methods 
for  useful  hints  in  culture,  and  the  culture  of  a  given 
plant  or  animal  should  be  based  more  or  less  upon  its 
natural  growth  conditions,  but  the  highest  progress  would 
be  impossible  if  we 'sought  only  to  imitate  nature. 

7.  Culture  Deals  witli  Life.    All  the  products  of  culture, 
whether  obtained  from  the  farm,  garden,  orchard,  nursery 
or  greenhouse,  proceed  directly  or  indirectly  from  plants 
or  animals,  both  of  which  are  lining  beings.     A  knowl- 
edge of  the  conditions  that  sustain  and  promote  life,  is, 
therefore,  the  foundation  to  a  broad  knowledge  of  hus- 
bandry. 

8.  What  is  Life?     We  know  nothing  of  life  except  as 
it  is  manifested  through  the  bodies  of  plants  and  animals. 
With  these,  we  can  define,  within   certain  limits,  the 
range  of  environment   in  which  it  can  exist;   we   can 
hinder  or  favor  it;  we  can  apparently  destroy,  but  we 
cannot  restore  it.     We  know  that  it  proceeds  from  a 
parental  body  similar  to  its  own,  that  the  body  it  inhabits 
undergoes  a  definite,  progressive  period  of  development, 
at  the  end  of  which  the  life  disappears  and  the  body 
loses  more  or  less  promptly  its  form  and  properties. 

9.  Vigor  and  Feebleness  are  terms  used  to  express  the 
relative  energy  manifested  by  the  life  of  different  living 
beings.    Certain  trees  in  the  nursery  row  usually  outstrip 
others  in  growth,  i.  e.,  are  more  vigorous  than  others. 


Introductory.  13 

One  pig  in  a  litter  very  often  grows  slower  than  any  of 
the  others,  i.  e.,  is  more  feeble  or  less  vigorous  than  any 
of  the  others.  Feebleness  is  the  opposite  of  vigor.  The 
most  vigorous  plant  or  animal  usually  attains  the  largest 
size,  and  as  a  rule,  is  most  satisfactory  to  its  owner. 
Vigor  is  promoted  by  a  favorable  environment.  It  is 
usually  greatest  in  rather  young  plants  and  animals,  and 
declines  with  advancing  age.  It  may  be  reduced  by 
disease  or  improper  treatment,  and  when  thus  reduced 
is  often  difficult  to  restore.  Keduced  vigor  tends  to  early 
maturity  and  shortened  life,  and  sometimes  to  increased 
prolificacy. 

10.  Hardiness  and  Tenderness  are  terms  used  to  express 
the  relative  power  possessed  by  different  plants  or  animals 
to  endure  extremes  in  their  environment.     The  Olden- 
burgh  apple  endures  with  little  harm  vicissitudes  of  tem- 
perature that  are  fatal  to  many  other  varieties;  in  other 
words,  it  is  hardier  as  regards  temperature  than  many 
other  varieties.     The  reindeer  is  hardier  as  regards  cold 
than    the    horse,   but   tenderer   as   regards   heat.     The 
melon  plant  is  hardier  as  regards  heat  and  drought  than 
the  lettuce,  but  tenderer  as  regards  wet  or  cold. 

11.  Health  and  Disease.     A  plant  or  animal  is  said  to 
be  in  health  when  all  its  organs  (parts)  are  capable  of 
performing  their  normal  functions.     An  organ  incapable 
of  doing  this,  or  the  being  possessing  such  an  organ,  is 
said  to  be  diseased. 

12.  The  Cellular  Structure  of  Living  Beings.     A  bit  of 

vegetable  or  animal  substance,  examined  under  a  micro- 
scope of  moderately  high  power,  is  seen  to  be  made  up 


14 


Principles  of  Plant  Culture. 


B 


of  numerous  little  sacks  or  cav- 
ities, more  or  less  clearly  defined, 
called  cells.  Cells  from  different 
beings,  or  from  different  parts 
of  the  same  being,  may  vary 
much  in  form  and  size,  but  they 
are  seldom  large  enough  to  be 

FIG.  1.    Showing  four   indi- 
vidual plants  of  a  species  of  seen  without  magnifying  power. 

Protocols.    A  shows  a  plant  Some      f  th       j  t       1{mt  d 

before  commencing  to  divide 

into  other  plants.    B,  c  and  D  animals   consist   of   single   cells 

show  how  the  cells  divide  to   (pj         1)        g  f    ^        } 

form    other     plants.     Highly    v 

magnified.  plants  consist  of  a  single  row  of 

cells  united  at  the  ends  (Fig.  2).     The  higher  plants 


Ii:AfoAfc 


'JW 


FIG.  2.  Part  of  a  filament  of  a  species  of  Spirogyra,  a  plant  consisting 
of  a  single  row  of  cells  united  at  their  ends.  The  places  where  the  cells 
join  are  indicated  by  the  vertical  lines.  Highly  magnified. 

and  animals  are  made  up 
of  many  cells  united,  and 
in  these,  the  cells  assume 
different  forms  and  prop- 
erties in  the  different  or- 
gans (Fig.  3).  In  some 
cases  the  united  cells  may 
be  readily  separated  from 
one  another,  which  shows 
each  cell  to  be  more  or 
less  an  independent  struct- 
ure. As  a  rule,  each  cell  FlG  3  Showingcellsof  the  apple  leaf 

is  Surrounded  by  its   OW11    in  a  section  from  its  upper  to  its  lower 

surface.  Highly  magnified.  The  spaces 
Closed  Cell- Wall.  marked  I  are  cavities  between  the  cells. 


Introductory.  15 

13.  Protoplasm  (pro' -to -plasm).     Living  cells  consist  of  * 
a  transparent,   jelly-like    substance   called   protoplasm, 
which  manifests  the  various  phenomena  of  life.     Proto- 
plasm may  exist  either  in  an  active  or  dormant  state.     In 
the  active  state  it  requires  both  nourishment  and  oxygen; 
in  the  dormant  state  it  may  exist  for  a  considerable  time 
with  very  little  of  either,  and  is  far  less  susceptible  to 
external  influences  than  in  its  active  state.     The  proto- 
plasm contained  in  plants  during  their  rest  period  (171), 
in  mature   air-dry  *   seeds,  .and   in   the  lower  animals 
during  their  torpid  condition,  is  in  the  dormant  state. 

14.  Reserve    Food.     Active    protoplasm    may    absorb 
nourishment  in  excess  of  immediate  requirements  and 
hold  it  as  reserve  food.     In  plants,  this  reserve  food  is 
in  the  form  of  starch,  sugar  or  oil;  in  animals  it  is  in  the 
form  of  fat.     These  substances  are  formed  by  the  proto- 
plasm from  its  crude  food  materials  (59).     The  reserve 
food  enables  the  plant  or  animal  to  live  through  limited 
periods  of  scarcity,  and  to  meet  the  demands  necessitated 
by  reproduction  (16). 

15.  Growth  is  the   normal,  permanent  change  in  the 
form  of  a  living  vegetable  or  animal  body,  and  is  usually 
accompanied  by  increase  in  size.     It  may  occur  either 
through  expansion  of  cells  already  formed,  or  through 
cell  multiplication.    The  latter  may  take  place  either  by 
division  of  older  cells  into  two  or  more  smaller  cells 
(Fig.  1),  or  by  the  formation  of  new  cells  within  older 
ones  —  the  young  cells  thus  formed  attaining  full  size  by 
subsequent  enlargement. 


*  Material  is  said  to  be  "air-dry  "  when  it  is  as  dry  as  it  will  become  by 
exposure  to  the  air  at  ordinary  temperatures. 


16  Principles  of  Plant  Culture. 

16.  Reproduction  is  the  increase  in  number  of  living 
beings.     It  is  one  of  the  properties  of  protoplasm  and  is 
essentially  a  process  of  division.     As  living  cells  mul- 
tiply by  forming  new  cells,  so  living  beings,  which  con- 
sist of  cells,  multiply  by  the  separation  of  a  part  of  their 
own  cells,  and  this  separated  group  of  cells  grows  into  a 
complete  organism  like  the  parent.     The  higher  plants 
multiply  by  seeds  (156),  which  are  separated  from  the 
parent  plant,  and  each  of  which  contains  a  young  plant 
(54).     The  eggs  from  which  young  birds  are  hatched 
contain  cells  filled  with  living  protoplasm,  and  the  pro- 
toplasm of  the  living  young  of  mammals  is  separated 
from  the  parent  before  birth. 

17.  Reproduction  is  either  Sexual  or  Non-Sexual.    Sexual 
reproduction  can  take  place,  as  a  rule,  only  upon  the 
union  of  cells  of  different  sexes.     It  is  not  peculiar  to 
the  animal  kingdom,  but  occurs  in  plants  also,  and  except 
in  rare  cases,  is  necessary  to  the  production  of  seeds  that 
are  capable  of  germination  (28).     It  is  the  only  method 
of  reproduction  in  the  higher  animals.     Sexual  repro- 
duction does  not  usually  take  place  until  the  period  of 
most  rapid  growth  has  passed.     Non-sexual  reproduction 
is  independent  of  sex.     It  results  from  the  direct  separa- 
tion of  a  part  of  the  parent,  which  under  favorable  con- 
ditions develops  into  a  complete  individual.     It  occurs 
when  plants  multiply  by  means  other  than  by  seeds,  as 
by  non- sexual  spores  (53),  bulbs  (352),   stolons  (348), 
cuttings  (358),  etc.,  and  it  is  a  common  method  of  re- 
production in  certain  of  the  lower  animals,  as  plant  lice 
(aphid*). 

18.  Heredity  and  Variation.     The  offspring  of  a  plant 
or  animal  tends  to  be  like  the  parent  or  parents.     But  no 


Introductory.  17 

two  beings  can  be  begotten  and  developed  in  exactly  the 
same  environment,  and  since  environment  always  affects 
the  individual  more  or  less,  it  follows  that  no  two  indi- 
viduals can  be  precisely  alike.  Variation  in  the  off- 
spring may  take  place  in  any  direction,  as  in  the  size  or 
color  of  the  flower,  the  sweetness  or  juiciness  of  the 
fruit,  the  prolificacy,  the  vigor  (9),  or  the  hardiness 
(10)  etc.  It  follows  that  in  culture  certain  individual 
plants  or  animals  are  more  desirable  to  the  cultivator 
than  others,  because  the  individuals  possess  different 
qualities. 

19.  The    Principle    of    Selection.     Since   the   offspring 
tends  to  resemble  the  parent  or  parents,  we  may  gradu- 
ally improve  plants  or  animals  in  the  direction  of  greater 
usefulness  by  selecting  the  most  desirable   individuals 
for  reproduction.    For  example,  by  saving  and  planting 
seeds  from  the  plants  that  produce  the  finest  petunia  or 
pansy  blossoms,  we  secure  finer  flowers  than  if  we  gather 
seeds  without  regard  to  parentage. 

20.  Breeding  in  plants  and  animals  is  reproduction, 
watched  over  and  directed  by  man,  with  reference  to 
securing  special  qualities  in  the  offspring.     It  is  based 
on  the  principle  that  the  peculiarities  of  the  parent  or 
parents  tend  to  be  reproduced,  and  may  be  intensified, 
in  the  descendants.     But  before  we  are  prepared  for  the 
study  of  breeding,  we  need  to  know  something  of  the 
principles  of  classification. 

21.  Classification  is  the  arrangement  of  the  different 
kinds  of  plants  and  animals  into  groups  and  families 
based  on  individual  resemblances.     If  we  examine  plants 
as  they  are  growing  in  nature,  we  may  observe  (a)  that 


18  Principles  of  Plant  Culture. 

there  are  many  plants  of  the  same  kind,  and  (6)  that  there 
are  many  kinds  of  plants.  The  different  plants  or  ani- 
mals of  the  same  kind  are  called  in<2t#tdtui&,and,in  general, 
we  may  say  that  the  different  kinds  of  plants  or  animals 
are  called  species  (spe-cies).  But  these  simple  distinctions 
are  not  sufficient  to  satisfy  the  needs  of  natural  history. 
We  might  say,  for  example,  that  the  violet  is  one  kind 
of  plant  and  the  oak  is  another,  which  is  true;  but  there 
are  also  different  kinds  of  violets  and  different  kinds  of 
oaks.  We  might  say  that  the  apple  is  one  kind  of  plant 
and  the  pear  is  another,  but  there  are  different  kinds  of 
apples,  as  the  crab  apple  and  the  common  apple,  and 
there  are  different  kinds  of  crab  apples,  and  of  common 
apples.  We  must  not  only  arrange  the  kinds  of  plants 
into  groups,  but  we  must  have  groups  of  different  grades. 
For  example,  botanists  call  each  distinct  kind  of  plant, 
as  the  sugar  maple,  the  white  oak  and  the  dandelion,  a 
species.  Then  the  species  that  rather  closely  resemble 
each  other  are  formed  into  groups,  each  of  which  is 
called  a  genus  (ge'-nus),  plural,  genera  (gen'-e-ra)  as 
the  sugar  maple  and  the  soft  maple;  the  white  oak,  the 
red  oak  and  the  bur  oak;  the  raspberry  and  the  black- 
berry; and  the  apple,  pear  and  quince.  Then  the  genera 
that  resemble  each  other,  as  the  one  containing  the  apple, 
pear  and  quince,  and  the  one  containing  the  plum,  cherry 
and  peach,  are  formed  into  other  groups  called  families.* 
Thus  families  are  made  up  of  genera,  and  genera  are  made 
up  of  species.  There  may  be,  also,  different  varieties  in 
the  same  species,  as  the  different  varieties  of  apple,  pea,, 
or  strawberry. 

*  Related  families  are  often  further  united  into  orders. 


Introductory.  1& 

An  extensive  retail  bookstore  furnishes  an  object  lesson 
in  classification,  though  we  must  remember  that  in 
natural  history  it  is  usually  the  names  and  descriptions 
of  plants  and  animals  that  are  classified,  and  not  the 
plants  and  animals  themselves.  In  the  bookstore,  we 
will  observe  that  the  books  are  not  placed  upon  the 
shelves  without  order,  but  that  they  are  arranged  in 
groups.  Different  copies  of  the  same  work  are  placed 
together.  Different  works  on  the  same  subject,  as  Gray's 
botany,  Wood' s  botany,  Bessey'  s  botany  are  also  placed 
in  a  larger  group.  Then  all  the  scientific  books  are 
formed  into  a  still  larger  group,  as  are  the  books  of 
fiction,  the  books  of  poetry,  the  music  books,  etc.  Com- 
paring this  arrangement  with  that  employed  in  natural 
history,  each  separate  work,  as  Gray's  Manual  of  Botany^ 
Thomas'  Fruit  Culturist,  Banyan's  Pilgrim's  Progress, 
etc.,  would  correspond  to  a  species,*  and  the  different 
copies  of  the  same  work  would  correspond  to  individuals. 
The  books  treating  of  the  same  general  subject,  as  the 
different  works  on  geology,  botany  or  arithmetic  would 
correspond  to  genera,  and  the  different  classes  of  books, 
as  scientific  books,  books  of  fiction,  etc.,  would  corres- 
pond to  families.  There  would  also  be  copies  of  the 
same  work  in  different  bindings  which  would  correspond 
to  .varieties. 

22.  Scientific  Names  are  given  to  plants  and  animals 
because  the  common  names  by  which  they  are  known  are 
so  often  local.  For  example,  quack  grass,  one  of  our 
common  troublesome  weeds,  is  known  by  at  least  seven 

*  It  should  not,  however,  be  understood  that  the  different  species 
of  plants  and  animals  are  always  as  readily  distinguished  as  are  the 
different  works  in  a  bookstore. 


20  Principles  of  Plant  Culture. 

different  common  names  in  this  country  alone,  and  yet, 
in  a  given  locality  it  is  often  known  by  only  one  name. 
Its  scientific  name,  however,  Agropyrum  repens  (a-gro- 
py'-rum  re'-pens),  is  the  same  in  all  languages  and 
countries.  Scientific  names  are  usually  Latin  and  con- 
sist of  two  words.  The  first  word  is  the  name  of  the 
genus  to  which  the  plant  or  animal  belongs,  and  is  called 
the  generic  (ge-ner'-ic)  name;  the  second  word  designates 
the  species,  and  is  called  the  specific  (spe-cif -ic)  name. 
For  example,  Purus  mains  (py'-rus  ma'lus)  is  the  scien- 
tific name  of  common  apple,  Purus  being  the  genus  to 
which  the  apple  belongs,  and  mains  designating  which 
species  of  the  genus  is  meant. 

23.  Crosses  and  Hybrids  (hy'-brids).  We  have  seen 
that  in  sexual  reproduction,  a  union  of  male  and  female 
cells  is  almost  always  essential  (17).  When  these  cells 
proceed  from  two  individuals  of  different  varieties  (21, 
436),  the  offspring  is  called  a  cross;  when  they  proceed 
from  individuals  of  different  species,  it  is  called  a  hybrid. 
Hybrids  are  possible  only  between  closely-allied  species 
and  are  often  incapable  of  reproduction,  in  which  case 
they  are  said  to  be  sterile.  The  mule,  which  is  a  hybrid 
between  the  horse  and  the  ass,  is  a  familar  example  of  a 
sterile  hybrid.  Sterile  hybrids  are  not  uncommon  in 
plants.  A  hybrid  that  is  capable  of  reproduction  is 
called  &  fertile  hybrid. 

Hybrids  and  crosses  may  resemble  both  parents  about 
equally  or  they  may  resemble  one  parent  more  than  the 
other.  They  sometimes  differ  materially  from  either 
parent.  The  offspring  of  crosses  and  fertile  hybrids  is 
generally  variable  in  proportion  as  their  parents  were 


Introductory.  21 

different  from  each  other,  and  this  variability  may  con- 
tinue through  several  generations. 

24.  The  Theory  of  Evolution,  now  generally  accepted 
by  naturalists,  assumes  that  the  higher  plants  and  ani- 
mals have  been  gradually  evolved  from   lower  forms, 
through  the  principle  that  those  individuals  possessing 
peculiarities  best  fitting  them  to  endure  the  adverse  con- 
ditions of  environment  have  survived  and  perpetuated 
their  kind,  while  others  have  perished. 

25.  Parasites.     Both  plants  and  animals  are  subject  to 
being  preyed  upon  by  other,  usually  smaller,  plants  and 
animals,  that  live  upon  or  within  their  bodies,  consuming 
the  tissues  of  their  bodies  or  their  reserve  food.     Plants 
or  animals  that   derive  their  nourishment  from   other 
plants  or  animals  are  called  parasites  ( par' -a- sites)  or 
parasitic.     The  plant  or  animal  from  which  a  parasite 
derives  its  nourishment  is  called  a  host.     Parasites  are 
often  microscopic  in  size.    They  are  generally  more  or  less 
injurious  to  their  host,  and  form  one  of  the  most  fruitful 
sources  of  disease  (271).     Some,  however,  as  the  micro- 
organisms of  the  roots  of  clover  and  other  leguminous 
plants,  are  beneficial  (113). 


CHAPTEK  II 
THE  ROUND  OF  PLANT  LIFE 

The  earliest  stages  of  plant  growth  occur  in  the  seed, 
hence  this  is  an  appropriate  place  to  commence  our  study. 
We  will  first  consider 

SECTION  I.    THE  BEHAVIOR  OF  SEEDS  TOWARD  WATER 

26.  Seeds  Absorb  Water  when  placed  in  contact  with 
it.     If  we  fill  a  bottle  with  air-dry  beans,  then  pour  in 
all  the  tepid  water  the  bottle  will  contain,  taking  care 
to  shake  out  the  air  bubbles,  and  place  the  bottle  in  a 
warm  room,  the  beans  will  soon  swell  until  they  have 
pressed  each  other  quite  out  of  shape,  and  no  water  will 
be   forced    out   of  the    bottle.      This    shows   that    the 
beans  have  absorbed  the  water  and  have  swollen  in  con- 
sequence.    This  quality  of  absorbing  water  by  contact, 
at  ordinary  temperatures,  is  possessed  to  a  greater  or  less 
extent  by  most  seeds,  and  indeed  by  nearly  all  air- dry 
vegetable  material.     It  is  unnecessary  that  the  seeds  be 
covered  with  water  to  enable  them  to  absorb  it.     If  in 
contact  with  any  moist  medium,  as  a  damp  cloth  or  damp 
earth,  they  will  absorb  moisture  and  swell. 

27.  The  Rate  at  which  Seeds  Absorb  Water  depends 
upon  several  conditions,  as 

a — The  water  content  of  the  medium  with  which  they 
are  in  contact.  If  we  place  one  lot  of  beans  in  water,  a 
second  in  wet  earth  and  a  third  in  slightly  damp  earth, 


Germination.  23 

we  shall  find  that  the  first  lot  will  swell  fastest,  the  second 
next  and  the  third  slowest.  Few  seeds  will  absorb  enough 
water  from  damp  air  at  ordinary  temperatures  to  swell 
much. 

b — The~  points  of  contact.  If  we  weigh,  two  lots  of 
100  beans  each,  on  a  delicate  balance,  and  mix  each  lot 
with  well-crumbled,  moist  loam  in  a  fruit  jar,  packing 
the  loam  tightly  in  one  of  the  jars  and  leaving  it  as 
loose  as  possible  in  the  other,  close  both  jars  to  prevent 
evaporation,  and  after  twenty-four  hours  sift  the  beans 
out  of  the  loam  and  weigh  the  two  lots  again  —  we  shall 
find  that  the  beans  in  the  jar  containing  the  compacted 
loam  have  increased  more  in  weight  than  the  others. 
This  indicates  that  the  beans  in  this  jar  have  absorbed 
water  faster  than  those  in  the  other,  because  they  were 
in  contact  with  the  moist  loam  at  more  points. 

c — Temperature.  If  we  fill  two  bottles  with  beans, 
adding  ice  water  to  one,  placing  it  in  a  refrigerator,  and 
lukewarm  water  to  the  other,  setting  it  in  a  warm  room, 
we  shall  find  that  the  beans  in  the  latter  bottle  will  swell 
more  rapidly  than  those  in  the  former.  This  shows  that 
a  warm  temperature  favors  the  absorption  of  water  —  a 
fact  that  is  true  of  all  seeds.  The  same  would  have  been 
true  had  we  planted  the  beans  in  two  samples  of  moist 
earth,  placing  these  in  different  temperatures. 

d — The  nature  of  the  seed-case.*    In  the  bean,  Indian 

*  The  term  seed-case  is  here  used  to  designate  the  outer  covering  of  the 
seed  as  the  word  seed  is  understood  by  the  seedsman  or  planter.  Every 
seed,  as  we  buy  it  in  the  market,  or  when  ready  for  planting,  has  one  or 
more  covering  layers.  In  the  peanut,  for  example,  what  we  here  call  the 
seed-case  is  commonly  called  the  shuck;  in  the  cocoanut  it  is  called  the 
shell;  in  the  bean  and  Indian  corn  it  is  more  often  called  the  skin.  In 
botany,  the  outer  coverings  of  seeds  are  given  different  names,  as  peri- 


24  Principles  of  Plant  Culture. 

corn,  wheat  and  many  other  seeds,  the  seed- case  is  of 
such  a  nature  that  it  absorbs  and  transmits  water  readily. 
In  certain  seeds,  however,  as  of  the  honey  locust,  canna, 
thorn  apple  etc.,  especially  if  they  have  been  allowed 
to  become  dry,  the  seed-case  does  not  readily  transmit 
water  at  growing  temperatures.  Such  seeds  may  lie  for 
weeks,  and  even  months,  in  tepid  water  without  swell- 
ing, but  when  the  water  is  heated  to  a  certain  degree, 
they  swell  promptly,  a  fact  often  turned  to  account  by 
nurserymen  (36).  We  cannot  always  judge  by  the  ap- 
pearance of  a  seed-case  whether  it  will  transmit  water 
readily  or  not. 

SECTION  II.     GERMINATION 

28.  What  is  Germination?  If  we  place  a  few  viable* 
grains  of  Indian  corn  between  the  moist  cloths  of  a  seed- 
tester  (Fig.  5),  cover  with  the  glass  and  place  in  a  warm 
room,  we  shall  observe  if  we  examine  the  corn  fre- 
quently, that  a  change,  aside  from  the  swelling,  will  soon 
take  place  in  at  least  a  part  of  the  grains.  The  seed- 
case  will  be  burst  by  the  pressure  of  a  tiny  white  shoot 
from  beneath.  We  say  that  such  grains  have  sprouted 
or  have  commenced  to  germinate  (ger'-mi-nate),  i.  e., 
have  taken  the  first  visible  step  toward  developing  into 
a  plant. 

We  have  seen  that  the  mature  seed  contains  proto- 
plasm in  its  dormant  condition  (13).  At  a  suitable  tem- 
perature, the  protoplasm,  on  the  absorption  of  water,  re- 
carp,  testa,  etc.,  according  to  their  exact  office  in  the  make-up  of  the  plant. 
To  avoid  explaining  the  technicalities  of  a  complex  subject,  it  seems  pre- 
ferable to  adopt  a  term  that  will  include  the  various  words  used  in  botany 
to  designate  the  outer  coverings  of  seeds. 

*  A  viable  (vi'-a-ble)  seed  is  one  that  is  capable  of  germination.  Not 
all  seeds  are  viable  (165). 


Germination.  25 

suiiies  its  active  state,  and  the  cells  of  a  certain  part  of 
the  seed  begin  to  increase  in  size  and  to  divide  (15), 
causing  the  tiny  shoot  to  burst  through  the  seed-case. 
Germination  is  completed  when  the  young  plant  (plant- 
let)  is  sufficiently  developed  to  live  without  further  aid 
from  the  seed. 

29.  Moisture    is    Essential    to    Germination.     Air-dry 
corn  or  other  seeds  will  not  germinate  if  kept  however 
long  in  a  warm  room,  whereas  viable  seeds,  that  have 
absorbed  water  until  fully  swollen,  will  usually  germi- 
nate if  exposed  to  air  of  a  suitable  temperature,  under 
conditions   that   prevent   their   loss  of  moisture.     This 
shows  that  a  certain  amount  of  moisture  must  be  absorbed 
by  the  seed  before  germination  can  take  place.     Seeds 
must  be  nearly  or  quite  saturated  with  water  before  they 
will  germinate. 

In  culture  we  plant  seeds  in  some  moist  medium,  usu- 
ally the  soil,  in  order  that  they  may  absorb  moisture  and 
germinate,  and  thus  develop  into  new  plants. 

30.  Warmth  is  Essential  to  Germination.   Had  we  placed 
the  seed-tester  mentioned  in  paragraph  28  in  a  refrigera- 
tor in  which  the  temperature  never  rises  above  46°  F., 
instead  of  in  a  warm  room,  the  corn  grains  would  not 
have  germinated  however  long   they  remained  there. 
This  shows  that  a  certain  degree  of  warmth  is  also  nec- 
essary to  germination.     Without  this,  the  protoplasm  ot 
the  seed  cannot  assume  its  active  state  (13).     The  low- 
est (minimum)  temperature  at  which  seeds  can  germi- 
nate varies  considerably  with  different  species,  and  so 
does  the  temperature  at  which  they  germinate  soonest 
(optimum)  as  also  the  highest  (maximum)  temperature 


26  Principles  of  Plant  Culture. 

at  which  they  can  germinate.  The  following  table* 
shows  approximately  the  minimum,  optimum  and  maxi- 
mum temperatures  at  which  seeds  of  the  species  named 
germinate. 

MINIMUM.  OPTIMUM.  MAXIMUM. 

Barley 41°  F 77°-88°  F 99°-lll°  F. 

Bean  (Scarlet  runner)....        41  77-88  88-99 

Buckwheat 41  93  115 

Clover  (red) 88-99  99  -111  Ill  -122 

Cucumber 60-65  88  -99  Ill  -122 

Flax 41  77  -88  88  -99 

Hemp 32-41  99-111  Ill  -122 

Indian  corn 41-51  99  -111  Ill  -122 

Lucern  (Alfalfa) 88-99  99  -111  Ill  -122 

Melon 60-65  88  -99  Ill  -122 

Oat 32-41  77  -88  88  -99 

Pea 32^11  77  -88  88  -99 

Pumpkin 51-60  93  -111  Ill  -122 

Rye 32-41  77  -88  88  -99 

Sunflower 41-51  88  -99  99  -111 

Wheat 32-41  77  -88  88  -108 

These  temperatures  refer  to  the  soil  or  other  medium 
with  which  the  seeds  are  in  contact,  and  not  to  the 
atmosphere. 

When  moisture  is  sufficient,  the  time  from  planting  to 
sprouting  decreases  rapidly  as  we  approach  the  optimum 
temperature.  In  an  experiment,  Indian  corn  sprouted 
in  one- third  of  the  time  at  88°  F.  that  it  required  to 
sprout  at  61°. 

31.  Free  Oxygen  is  Essential  to  Germination.  If  we  place 
in  the  bottom  of  each  of  two  saucersf  a  layer  of  puddled  J 


*  Compiled  from  Haberlandt  and  Sachs. 

f  If  flower-pot  saucers  are  used  they  should  first  be  well  soaked  in 
water,  so  that  they  will  not  extract  water  from  the  soil. 

t  Soil  is  said  to  be  puddled  when  wet  and  packed  until  it  is  in  the  con- 
sistency of  putty. 


Germination.  27 

<;lay  or  loam,  put  25  viable  beans  on  the  soil  in  each  saucer, 
then  fill  one  saucer  with  moist  sand  and  the  other  with 
puddled  clay  or  loain,  pressing  the  latter  down  very 
closely  around  the  beans,  cover  both  saucers  with  a  bell- 
jar,  and  place  in  a  warm  room  for  two  or  three  days,  we 
shall  find  that  the  beans  covered  with  the  sand  will 
sprout  promptly,  while  those  covered  with  the  puddled 
soil  will  not  (Fig.  4).  In  the  sand-covered  saucer  the 


FIG.  4.  In  the  left  hand  saucer  beans  were  planted  in  puddled  soil.  In 
the  other,  they  were  covered  with  sand.  They  failed  to  germinate  in  the 
puddled  soil,  because  their  contact  with  oxygen  was  cut  off.  (From  nature). 

air  between  the  grains  of  sand  has  had  access  to  the 
beans,  while  in  the  other  the  air  has  been  shut  out,  which 
explains  the  sprouting  of  one  lot  of  seeds  and  the  failure 
of  the  other.  About  one-fifth  of  the  atmosphere  is  free 
oxygen,  i.  e.,  oxygen  that  is  not  chemically  combined 
with  any  other  substance. 

We  have  seen  that  protoplasm  in  its  active  state  re- 
quires oxygen  (13).  Unless  seeds  are  so  planted  that  a 
certain  amount  of  this  free  oxygen  can  reach  them  they 
cannot  germinate.*  Ordinary  water  contains  a  little  free 
oxygen,  but  not  enough  to  enable  many  kinds  of  seeds 
to  germinate  in  it,  though  the  seeds  of  some  water  plants, 
as  the  water  lily  and  rice  will  germinate  in  water.  But 
even  these  will  not  germinate  in  water  that  has  been 

*  This  probably  explains  why  very  deeply-planted  seeds  rarely  germi- 
nate. 


28 


Principles  of  Plant  Culture. 


boiled  long  enough  to  expel  the  oxygen,  and  is  placed 
under  conditions  that  prevent  its  absorption  again 
(Fig.  5). 

We  thus  see  that  seeds  require  three  conditions  before 
they  can  germinate,  viz.,  a  certain  amount  of  moisture, 
of  warmth  and  of  oxygen.  In  planting  seeds,  we  should 
consider  all  these  requirements. 

32.  Prompt  Germination  is  Important.     As  a  rule,  the 
sooner  a  seed  germinates  affer  it  is  planted,  the  better 
for  it  is  generally  in  danger  of  being  destroyed  by  ani- 
mals or  fungi,  and  the  plantlet  probably  loses  vigor  by 

too  slow  develop- 
ment. Weeds  may 
also  be  gaining  a 
start  i  f  germiua: 
tion  i  s  delayed. 
We  should,  there- 
fore, treat  both  the 
seed  and  the  soil  in 
the  way  that  fav- 
ors prompt  germi- 
nation. 

FIG.  5.  In  the  left  bottle,  the  water,  which  had  been  boiled  to  expel 
the  oxygen,  was  covered  with  oil  to  prevent  it  from  absorbing  oxygen 
again,  hence  the  rice  seeds  in  it  could  not  germinate.  In  the  right  bottle, 
the  water  was  not  covered,  and  so  could  absorb  oxygen,  permitting  the 
seeds  to  germinate.  From  nature. 

33.  Compacting  the  Soil  about  planted  seeds  Hastens 
Germination  by  multiplying  their  points  of  contact  with 
the  moist  earth  (276).     When  the  soil  is  becoming  drier 
day  by  day,  as  it   often  is  in  spring,  compacting  the 
soil  about  planted  seeds  materially  hastens  their  germi- 
nation and  often  secures  germination  that  without  the 


Germination.  29 

compacting  might  be  indefinitely  postponed.  The  hoe, 
the  feet,  a  board  or  the  hand-  or  horse  roller  may  be 
used  to  compact  soil  over  planted  seeds. 

34.  Planting  should  be  Deferred  until  the  Soil  becomes 
Warm.     Seeds  cannot  germinate  promptly  until  the  tem- 
perature of  the  soil  in  which  they  are  planted  approaches 
the   optimum   for   their    germination   (30)   during   the 
warmer  part  of  the  day,  and  germination  is  promoted 
little,  if  at  all,  by  planting  Before  this  time. 

35.  Excess  of  Water  in  the  soil  Retards  Germination  by 
restricting   the   supply  of  oxygen  (31),  and  sometimes, 
by  keeping  the  soil  cold.     Seeds  should  not  be  planted 
in  soil  wet  enough  to  puddle  (31)  about  them,  nor  should 
the  soil  in  which  the  seeds  of  land  plants  are  planted  be 
so  freely  watered  that  the  seeds  remain  surrounded  with 
liquid  water,  thus   shutting   out  the   normal   supply  of 
oxygen. 

36.  Germination  may  be  Hastened  by  Soaking  seeds  be- 
fore planting.    Since  seeds  cannot  germinate  until  nearly 
or  quite  saturated  with  water  (29),  and  since  they  absorb 
water  faster  from  a  very  wet  than  from  a  damp  medium 
(27a),  and  in  a  warm  than  in  a  cool  temperature  (27c)7 
we  may  hasten  germination  a  little  if  the  soil  to  receive 
the  seeds  is  only  slightly  moist,  by  soaking  the  seeds 
before  planting  in  warm  or  slightly  hot  water  until  they 
have  swollen.     This  method  is  sometimes  practiced  by 
gardeners  with  sweet  corn  and  certain  other  seeds,  and 
its  use  might  possibly  be  extended  with  profit.    The  water 
should  be  heated  only  to  110°  or  120°  F.  and  the  soaking 
may  be  continued  until  the  seeds  have  fully  swollen. 

Soaking  is  most  important  with   seeds  having  seed- 
cases  that  do  not  readily  transmit  water  at  growing  tern- 


30  Principles  of  Plant  Culture. 

peratures,  as  in  the  honey  locust,  canna,  thorn  apple 
etc.  (27d).  Such  seeds,  particularly  if  they  have  been 
allowed  to  become  dry,  are  generally  soaked  in  hot  water 
until  swollen,  before  planting,  otherwise  they  might  lie 
in  the  ground  for  months  and  even  years  before  germi- 
nating. In  treating  such  seeds  with  hot  water,  unless  the 
temperature  at  which  they  swell  is  known,  the  water 
should  be  heated  very  gradually  until  the  seeds  begin  to 
swell,  when  it  should  be  maintained  at  that  temperature 
until  they  are  fully  swollen.  It  is  said  that  seeds  of  the 
honey  locust  may  be  immersed  for  a  time  in  boiling  water 
without  destroying  their  vitality,  but  such  treatment  is 
not  to  be  recommended  for  any  seeds.  In  seeds  of  this 
class, 

37.  Germination  is  sometimes  Hastened  by  Cracking  or 
Cutting  Away  part  of  the  Seed-Case.    To  favor  the  absorp- 
tion  of  water,    nurserymen   otten   drill   or   file  a   hole 
through   the   bony   seed-cases  of  nelumbium   seeds,   or 
crack  dry  peach  and  plum  pits  in  a  vise  or  with  an  im- 
plement resembling  a  nutcracker  (27d). 

38.  Seeds  may  Fail  to  Germinate  from   a   variety  of 
causes,  even   when    exposed  to  the   proper   degree   of 
warmth,  moisture  and  oxygen.     They  may  be  too  old 
(165),  they  may  not  have  been  sufficiently  mature  when 
gathered  (163),  they  may  have  become  too  dry  (169), 
they  may  have  been  subjected  to  freezing  before  suffi- 
ciently dry   (167),  they  may  have   been  stored  while 
damp  and  thus  subjected  to  undue  heating,  or  they  may 
have  been  damaged  by  insects  or  fungi  (321)  either  be- 
fore or  after  maturity.     Defects  of  these  kinds  are  not 
always  visible,  hence 


Germination.  31 

39.  Seeds  should  be  Tested  before  Planting  to  learn  if 
they  will  germinate.  It  is  unnecessary  to  plant  seeds  in 
soil  to  test  them,  since  the  seed-tester  shown  in  Fig.  6  is 
much  more  convenient.  This  useful  device  consists  of 
two  circular  pieces  of  clean,  moderately  thick  cloth  of 
rather  loose  texture,  a  table  plate  that  is  not  warped,  and 
a  pane  of  glass  large  enough  to  cover  the  plate.  The 
cloths  are  dipped  in  water,  and  squeezed  a  few  times 
while  under  the  water  to  press  out  the  air.  They  are 


FIG.  6.    Showing  a  simple  seed-tester,  adapted  to  farmers'  and  garde- 
ners' use. 

then  wrung  out  until  moderately  wet,  and  spread  over 
the  bottom  of  the  plate  as  shown,  and  the  seeds  to  be 
tested  are  placed  between  them.  It  is  well  to  use  a  hun- 
dred or  more  seeds  of  each  sample,  as  a  larger  number 
will  show  the  per  cent  of  vitality  more  accurately  than 
a  smaller  one,  and  the  lot  should  always  be  well  mixed 
before  taking  the  sample.  The  plate  should  be  kept  cov- 
ered with  the  glass  to  prevent  evaporation  from  the 
cloths,  and  it  may  be  placed  in  any  room  of  comfortable 
living  temperature.  The  seeds  should  be  frequently  ex- 
amined, and  may  be  removed  as  they  sprout,  when  by 


32  Principles  of  Plant  Culture. 

subtracting  the  number  that  fail  to  sprout  from  the  num- 
ber put  in,  the  per  cent  of  vitality  may  be  readily  com- 
puted. The  cloths  should  be  placed  in  boiling  water  a 
few  minutes  before  using  them  for  a  second  test,  to  de- 
stroy any  spores  or  mycelia  of  mold  with  which  they 
may  have  become  infected. 

40.  The  Time  Required  for  Germination  varies  greatly 
in  different  kinds  of  seeds.  In  lettuce  seed,  the  tiny 
white  shoot  often  breaks  through  the  seed-case  within 
twenty-four-  hours  from  planting,  while  celery  seed  re- 
quires several  days  to  germinate  to  this  extent.  The 
seeds  of  many  plants  will  not  germinate  the  same  season 
thej<  are  formed,  even  if  planted  under  the  most  favor- 
able conditions  (163). 

Individual  seeds  of  the  same  kind  and  of  the  same 
sample  often  vary  greatly  in  the  time  required  for  ger- 
mination. Even  in  seeds  that  germinate  soonest,  as  let- 
tuce and  radish,  some  individuals  will  not  germinate 
until  several  days  after  the  majority  have  germinated. 
Seeds  of  tobacco  and  purslane*  sometimes  continue  to 
germinate  through  several  successive  seasons.  The  rea- 
sons for  these  variations  are  not  known. 

SECTION  III.     THE  PLANTLET 

By  watching  the  germination  of  seeds,  we  may  learn 
some  interesting  facts.  Viable  seeds  will  usually  germi- 
nate freely  on  the  surface  of  well-moistened  soil  or  sand, 
if  we  provide  a  damp  atmosphere  above  them  by  cover- 
ing with  a  bell-jar  or  otherwise,  for  light  does-not  hinder 
germination.  One  of  the  interesting  facts  connected 
with  germination  is,  that  the  first  shoot,  called 

*  Portulaca  oleracea. 


The  Flantlet.  33 

41.  The  Hypocotyl*  (hy'-po-co'-tyl)  Grows   Downward, 

on  emerging  from  the  seed-case  (27d),  no  matter  in  what 
position  the  seed  is  placed.  It  will  curve  in  a  semi- 
circle if  necessary,  to  bring  its  rounded  point  in  contact 
with  the  soil.  But  the  hypocotyl  is  not  always  able  to 
enter  the  soil,  unless  the  seed  is  covered  more  or  less,  be^ 
cause  the  resistance  offered  by  the  soil  is  often  greater 
than  the  weight  of  the  seed.  On  this  account,  as  well  as 
to  insure  a  supply  of  moisture,  it  is  best  to  cover  most 
seeds  at  planting,  or  at  least  to  press  them  well  into  the 
soil  (52).  In  nature,  seeds  usually  become  more  or  less 
covered,  and  those  not  covered  generally  fail  to  germinate. 

42.  The  Seed-Case  in  Germination.     After  germination 
commences,  the  seed-case  is  of  no  further  use.     It  has 
fulfilled  its  purpose,  which  is  to  protect  the  seed  from 
the  time  of  its  maturity  until  the  conditions  arrive  for 
germination,  and  is  henceforth  a  hindrance  to  germina- 
tion in  many  plants,  as  it  must  be  torn  asunder  by  the 
expanding  plantlet.     If  we  watch  the   germination   of 
squash  or  pumpkin  seeds  through  the  different  stages, 
we  may  discover  that  nature  has  made  a  special  provis- 
ion to  help  the  plaiitlet  in  escaping  from  the  seed- case 
in  these  plants.     As  the  hypocotyl  curves  downward,  a 
projection  or  hook  is  formed  on  the  side  toward  the  seed, 
which  holds  the  seed- case  down  while  the  seed-leaves  are 
pulled  out  from  it.     The  action  of  this  hook  is  shown  in 
the  accompanying  figures.     Sometimes,  as  shown  in  C, 
the  point  of  the  seed-case  breaks,  permitting  the  hook 
to  slip  off,  and  if  the  seed  happens  to  be  planted  edge- 
wise or  with  the  point  downward,  the  hook  often  fails 

*  Often  called  radicle  and  caulicle. 


34 


Principles  of  Plant  Culture. 


to  catch  the  seed- case,  as  in  D,  and  so  the  plantlet 
emerges  from  the  soil  without  freeing  itself  from  the  seed- 
case  and  is  hampered  for  a  time.  This  provision  is 
peculiar  to  the  pumpkin  family,*  to  which  the  pumpkin, 
squash,  cucumber  and  melon  belong,  though  other  pro- 
visions which  accomplish  the  same  end  are  found  in  a 
few  other  families,  but  many  plants  are  considerably  held 
back  by  the  seed-case  during  germination. 


FIG.  7.  Showing  nature's  provision  to  enable  the  pumpkin  plantlet 
to  escape  from  the  seed-case.  In  A,  the  hook  on  the  hypocotyl  is  attached 
to  the  lower  half  of  the  seed-case.  B  shows  the  same  after  germination  is 
farther  advanced.  A  fully-germinated  pumpkin  plantlet  is  shown  at  Fig.  8. 

43.  Seeds  of  the   Pumpkin    Family  should  be  Planted 
Flatwise,  rather  than  edgewise  or  endwise,  since  in  this 
position  they  most  readily  free  themselves  from  the  seed- 
case. 

44.  Some  Plantlets  Need  Help  to  Burst  the  Seed-Case. 
In  many  seeds  having  hard  and  strong  seed -cases,  as  the 
walnut,  butternut  and  hickory  nut  and  the  pits  of  the 


*  Natural  order  Cucurbitaceee. 


The  Plantlet. 


35 


plum,  peach  and  cherry,  the  enlarging  plantlet  is  often 
unable  to  burst  the  seed- case,  hence  germination  cannot 
take  place  unless  assisted  by  the  expanding  power  of 
frost,  or  long  exposure  to  moisture  which  softens  the 
seed- case,  or  unless  the  seed  -case  is  cracked  before  the 
seeds  are  planted  (37). 

45.  The  Roots  promptly  start,  as  the  hypocotyl  emer- 
ges from  the  seed-case  —  the  main  (primary)  root  from 
its  point,  and  the  branch  (lateral)  roots  from  its  side. 
Sometimes  root-hairs  (101)  may  be  distinctly  seen,  espe- 
cially when  seeds  germinate  in  the  seed-tester  (39). 

By  studying  Figs.  8  to  11,  we  may  learn  more  of  the 
germinating  process. 


FIG.  8.    Plantlet    FIG.  9.    Plantlet    FIG.  10.    Plantlet    FIG.  11.    Plantlet 
of  pumpkin.  of  bean.  of  Indian  corn.  of  pea. 

In  the  pumpkin  and  bean,  the  seed-leaves  (cotyledons)  are  lifted  above 
the  surface  of  the  soil  in  germination. 

In  the  pea,  the  cotyledons  are  not  lifted  above  the  surface  of  the  soil  in 
germination. 


36  Principles  of  Plant  Culture. 

46.  The  Cotyledons  (co-ty-le'-dons).     In  the  bean  and 
pumpkin,  the  seed,  or  what  remains  of  it,  seems  to  have 
separated  into  two  parts  that  are  united  at  one  end  —  the 
cotyledons  or  seed-leaves.     In  the  bean  and  pumpkin,  the 
cotyledons  form  a  pair  of  clumsy  leaves,  which  in  the 
bean,  point  downward  at  first,  but  afterwards  become  up- 
right, by   the   straightening  of  the   hypocotyl   beneath 
them.     We  observe  that  the  pea  has  also  a  pair  of  coty- 
ledons (c),  which  have  not  separated  to  the  same  extent 
as  those  of  the  bean  and  pumpkin  and  are  still  beneath  the 
soil.     The  corn,  in  common  with  other  plants  of  its  class, 
as  sorghum,  sugar  cane,  the  reeds,  grasses,  etc.,  has  but 
one  cotyledon,  and  that  is  not  easily  seen  without  dis- 
secting  the   seed.     In   Fig.  14,  which   shows   a   cross- 
section  of  the  germinating  corn  grain,  the  cotyledon  ap- 
pears at  cot. 

The  plants  having  two  cotyledons  form  a  very  import- 
ant class  in  botany,  known  as  Dicotyledones  (di-co-tyl-e'- 
dones);  those  having  but  one  cotyledon  form  a  class 
known  as  Monocotyledones  (ino'-iio-co-tyl-e'-dones). 
There  is  also  a  class,  including  the  pine,  fir  and  other 
conifers,  that  have  several  cotyledons. 

47.  The    Hypocotyl    Develops    Differently   in    Different 
Species.     In  the  pea  (Fig.  11)  and  some  other  plants, 
the   cotyledons  remain   in  the  soil,  while  in  the  bean 
and  pumpkin,  they  have  been  lifted  bodily  into  the  air. 
This  striking  difference  is  due  to  the  fact  that  in  the 
pea,  the  hypocotyl  lengthens  very  little  in  germination, 
while  in  the  bean  and  pumpkin,  it  lengthens  compara- 
tively very  much. 

48.  Seeds  in  which  the  Hypocotyl  Lengthens  in  germi- 
nation Must  Not  be  Deeply  Planted.     When  seeds  of  this 


The  Plantlet. 


37 


class,  which  includes  many  plants  beside  the  bean  and 
pumpkin,  are  planted  in  soil,  the  cotyledons  must  be 
forced  through  the  soil  above 
them,  an  act  requiring  consider- 
able energy.  If  such  seeds  are 
covered  with  much  soil,  the 
plantlet  is  often  unable  to  lift  its 
cotyledons  to  the  surface,  and 
hence  must  perish.  Fig.  12 
shows  two  bean  plantlets  that 
tore  off  their  cotyledons  in  the 
vain  attempt  to  lift  them  through 
five  inches  of  soil.  The  plantlet 
of  wheat,  barley  and  oats,  though 
much  smaller  and  weaker  than 
that  of  the  bean,  readily  grows 
through  this  depth  of  soil,  be- 
cause the  tiny  pointed  shoot  (plu- 
mule (56))  of  these  plants 
readily  insinuates  itself  between  the  soil  particles  and 
conies  to  the  surface  with  little  expenditure  of  energy, 
even  when  deeply  planted.  Plantlets  of  the  larger  beans 
usually  fail  if  the  seeds  are  planted  three  inches  deep  in 
a  clay  soil  that  bakes  above  them.  Those  of  the  castor 
bean,*  though  very  robust,  can  hardly  lift  their  cotyle- 
dons through  one  inch  of  soil,  while  those  of  the  pea,  though 
much  more  slender,  readily  grow  through  four  to  six 
inches.  Apple  seeds  planted  in  autumn  on  clay  soil, 
usually  fail  to  germinate  the  following  spring  unless 
covered  with  sand  or  hunius,  or  carefully  mulched,  be- 
cause the  plantlets  are  unable  to  lift  their  cotyledons 
through  a  baked  surface  soil. 


FIG.  12.  Showing  two  bean 
plantlets  that  tore  off  their 
cotyledons  from  being  too 
deeply  planted. 


*  Bicinus. 


38 


Principles  of  Plant  Culture. 


49.  The  Vigor  of  the  Plantlet  is  generally  in  Proportion 

to  the  Size  of  the  Seed.  This  is  true  not  only  between 
different  kinds  of  seeds,  but  between  different  seeds  of 

the  same  kind. 
The  larger 
beans,  the  horse 
chestnut  and 
the  walnut  form 
much  stronger 
plantlets  than 
clover,  timothy 
a  n  d  tobacco, 
and  the  largest 
and  plumpest 

FIG.  13.    Showing  navy  bean  plants  grown  from   gpeci  m  e  11  S   O  f 
large  seeds  (left)  and  from  small  seeds  (right). 

any  sample   ot 

seed  usually  form  stronger  plantlets  than  the  smaller  and 
more  shrunken  specimens.  Growers  of  lettuce  under 
glass  are  sometimes  able  to  raise  one  more  crop  during 
the  winter  by  sowing  only  the  largest  seeds  than  when 
the  seed  is  sown  without  sifting.  The  practice  of  sifting 
seeds  before  planting,  and  rejecting  the  smaller  ones, 
should  be  more  generally  followed  (Fig.  13). 

50.  The   Earlier  Germinations  from  a  sample  of  seed 
often  Form  More  Vigorous  Seedlings  than  the  Later  Ones. 
This  is  one  of  nature's  methods  for  preserving  the  vigor 
of  plants.     The  stronger  seedlings  overtop  the  later  and 
feebler  ones  and  crowrd   them  out   of  existence.     We 
should  profit  by  this  hint  and  reject  the  later  plants  in 
the  seed-bed. 

51.  How  Deep  should  Seeds  be  Planted?    We  have  seen 
that  one  object  of  planting  seeds  in  the  soil  is  to  place 


The  Plantlet.  39 

them  in  contact  with  moisture  (29).  Since  the  plantlet 
must  force  its  way  through  the  soil  that  covers  the  seed, 
the  less  the  depth  of  this  soil,  other  things  equal,  the  less 
energy  and  the  shorter  time  are  required  for  the  plantlet 
to  reach  the  surface.  Therefore,  seeds  should  not  be  planted 
deeper  than  is  necessary  to  insure  the  proper  supply  of  moisture. 
Small  seeds,  as  of  lettuce,  celery  and  carrot,  produce 
such  weak  plantlets  that  it  is  unsafe  to  cover  them  suf- 
ficiently to  insure  the  proper  moisture  supply  in  dry 
weather.  We  must,  therefore,  plant  such  seeds  so  early 
in  spring  that  the  soil  has  not  had  time  to  become  dry, 
or  if  necessarily  planted  later,  we  must  depend  largely 
upon  artificial  watering. 

52.  Very  Small  Seeds,  as  of  petunia  and  tobacco,  Should 
Not  Be  Covered  with  soil  at  all,  but  may  be  pressed  down 
into  fine  loam  with  a  board  or  otherwise,  and  must  be 
watered  often  with  a  fine- rose  watering-pot.    When  small 
seeds  are  sown  in  full  exposure  to  sunlight,  it  is  well  to 
shade  the  surface  with  paper  or  a  muslin-covered  frame, 
to  check  evaporation  until  the  plantlets  appear.     Small 
seeds  are  sometimes  covered  with  a  thin  layer  of  sphag- 
num moss  that  has  been  rubbed  through  a  sieve.     This 
helps  to  retain  moisture  in  the  surface  soil. 

53.  Ferns  are  Grown  from  Spores*  sown  on  the  surface 
of  fine  soil  in  a  propagating  frame  (369),  in  which  the 
air  is  kept  very  moist  and  the  surface  of  the  soil  never 
becomes  dry. 

*  Spores  are  the  chief  reproductive  bodies  in  plants  that  produce  no 
seed,  as  ferns,  mushrooms,  mosses,  etc.  They  are  usually  so  small  as  to 
be  barely  visible  to  the  unaided  eye.  The  dust  that  escapes  from  a  puff- 
ball  when  it  is  squeezed  or  from  a  bunch  of  corn  smut  is  formed  of  the 
spores  of  these  plants.  Spores  usually  consist  of  a  single  cell,  in  which 
respect  they  differ  materially  from  seeds,  which  contain  a  more  or  less 
developed  plantlet  (54). 


40  Principles  of  Plant  Culture. 

54.  The  Plantlet  is  Visible  in  the  Seed.    If  we  boil  seeds 
of  the  four  kinds  shown  in  Figs.  8  to  11,  or  of  other 
kinds,  in  water  until  they  are  fully  swollen,  and  then 
carefully  dissect  them  with  the  forceps  and  needle,  using 
the  magnifying  glass  when  necessary,  we  may  observe 
that  the  plantlet  is  present  compactly  folded  up  in  the 
seed.     Germination  (28)  is  really  little  more  than  the 
unfolding  and  expansion  of  this  plantlet.     The  pl^itlet 
as  it  exists  in  the  seed  is  called  the  embryo  (em'-bry-o). 

55.  The  Endosperm*  (en'-do-sperm).     From  the  sec- 
tion of  the  corn  grain  shown  in  Fig.  14,  it  appears  that 
in  this  seed,  unlike   the   pea,  bean  and   pumpkin,  the 


FIG.  14.  Cross-section  of  germinating  Indian  corn  grain.  A  endo- 
sperm; Cot  cotyledon;  Can  hypocotyl;  PI  plumule.  Slightly  magnified. 
(After  Frank). 

plantlet  and  seed- case  do  not  make  up  the  whole  bulk  of 
the  seed.  The  remaining  part  shown  at  A,  consists 
mainly  of  cells  containing  starch  grains  and  oil  drops, 
which  serve  as  food  for  the  plantlet  during  germination, 


Called  also  albumen. 


The  Plantlet.  41 

since  active  protoplasm  cannot  exist  without  nourish- 
ment (13).  In  the  pea,  bean,  pumpkin  and  other  seeds 
of  this  class,  the  food  supply,  instead  of  being  stored  by 
itself,  as  in  the  corn-grain,  is  contained  within  the  plant- 
let  or  embryo  —  mainly  in  the  fleshy  cotyledons.  When 
the  food  supply  of  the  seed  is  separate  from  the  embryo, 
as  in  corn  and  many  other  seeds,  it  is  called  the  endosperm. 
It  is  the  food  supply  of  seeds  that  makes  them  so  val- 
uable as  food  for  animals. 

56.  The  Plumule  (pi  u' -mule).     If  we  look  between  the 
cotyledons  of  the  bean  plantlet  (Fig.  9),  at  the  point  of 
their  union  with  the  hypocotyl,  we  may  see  a  pair  of 
tiny  leaves,  and  by  carefully  separating  these  if  need  be, 
with  the  point  of  a  pin,  we  may  discover  a  minute  pro- 
jection—  the   growing  point  (67)  of  the  stem  between 
them.     These  leaves,  with  the  growing  point,  form  the 
plumule  —  the  terminal  bud  of  the  plantlet.     These  tiny 
leaves  become  the  first  true  leaves,  and  the  growing 
point  between  them  develops  into  the  stem  and  later 
leaves.     By  close  examination,  we  may  make  out  the 
plumule  in  Figs.  8,  10  and  11.     In  the  pea  and  corn,  it 
has  already  made  considerable  growth. 

57.  Thus  we  see  that  the  plantlet  or  seedling  consists 
of  three  parts,  viz.,  the  hypocotyl,  the  cotyledons  (in 
some  plants  cotyledon)  or  seed-leaves,  and  the  plumule 
or  terminal  bud. 

58.  Chlorophyll  (chlo'-ro-phyll).     Soon  after  the  plant- 
let  emerges  from  the  seed- case,  a  green  color  appears  in 
the  parts  most  exposed  to  light.     This  is  due  to  the  for- 
mation within  the  cells  of  chlorophyll  —  the  green  color- 
ing matter  of  plants.      Chlorophyll  forms  only  in  light,  and 

3 


42 


Principles  of  Plant  Culture. 


when  a  plant  containing  green  leaves  is  kept  for  a  time 
in  the  dark,  as  when  celery  is  banked  up  with  earth,  the 
chlorophyll  disappears  and  the  green  parts  become 
white.  The  chlorophyll  saturates  definite  particles  of 
protoplasm,  called  chlorophyll  bodies,  and  since  the  cell- 
walls  and  protoplasm  are  transparent  in  the  younger 
cells,  the  chlorophyll  bodies  give  the  parts  containing 


ep 


FIG.  15.  Showing  cross-section  through  leaf  of  Fagus  sylvatica.  C 
•chlorophyll  bodies;  Ep  epidermis  of  upper  surface  of  leaf;  Ep"  epider- 
mis of  lower  surface;  K  cells  containing  crystals;  PI  palisade  layer;  F 
"vascular  bundle;  8t  stoma;  I  spaces  between  the  cells  (intercellular 
spaces).  Highly  magnified.  (After  Strasburger). 

them  a  green  color.  Fig.  15  shows  the  distribution  of 
the  chlorophyll  bodies  in  the  cells  of  a  portion  of  a  leaf 
of  the  beech.  They  appear  as  minute  globules,  which  in 
this  case  are  mostly  located  near  the  cell- walls.  They 
are  most  numerous  near  the  upper  surface  of  the  leaf — 
the  part  most  exposed  to  the  sun's  rays. 

59.  No  Food  can  be  formed  Without  Chlorophyll.  By 
the  agency  of  chlorophyll,  the  chlorophyll  bodies  absorb 
energy  in  the  form  of  light.  This  energy  the  chloro- 
phyll body  uses  to  take  to  pieces  the  carbonic  acid,  min- 
eral salts  and  water  absorbed  from  the  air  and  the  soil, 


The  Plantlet.  43 

and  to  recombine  them  into  foods  of  various  kinds  which 
can  be  used  by  the  protoplasm  in  making  new  parts  and 
in  repairing  waste  (Assimilation  (as-sini'-i-la'-tion)). 
Until  this  food  preparation  commences,  no  new  plant  sub- 
stance has  been  formed.  It  is  true  that  new  cell -walls 
and  new  protoplasm  may  be  formed  from  the  food  sup- 
ply of  the  seed  before  chlorophyll  appears,  but  until 
chlorophyll  is  formed,  and  food  preparation  begins,  the 
whole  plantlet  with  whatever  remains  of  the  seed,  when 
dried,  weighs  no  more  than  the  seed  weighed  at  the  be- 
ginning. The  material  formed  for  food  is  starch,  or  some 
substance  of  similar  composition  (sugar  or  oil),  which, 
after  undergoing  chemical  changes  if  need  be,  to  render 
it  soluble,  is  distributed  throughout  the  plant  to  be  built 
up  into  cell-walls  and  protoplasm,  or  to  be  held  as  reserve 
food  (14).  * 

Food  preparation  and  assimilation 
are  not  necessarily  simultaneous,  but 
either  may  proceed  without  the  other. 
Only  plants  can  prepare  food  from 
mineral  substances.  The  food  of  ani- 
mals must  all  have  been  first  formed 
by  plants. 

60.  The  Sources  of  Plant  Food.    By 
FIG.  16.     showing  observing   plantlets  of  the  bean  or 

starch  crystals  stored  as  pumpkin  a  few  days  after  germina- 
reserve  food  in  a  cell  of  J 

potato.  Highly  magni-  nation,  we  may  discover  that  the  coty- 
ledons, which  were  at  first  so  plump, 
have  shriveled  to  a  mere  fraction  of  their  former  size. 
This  change  is  due  to  the  fact  that  the  food  contained  by 
these  parts  has  been  absorbed  by  the  developing  plant- 
let.  The  patrimony  furnished  by  the  seed  is  quickly  ex- 


44  Principles  of  Plant  Culture. 

hausted.  Whence  then  comes  the  food  that  is  to  com- 
plete the  development  of  the  plant?  Aside  from  the 
carbonic  acid  already  mentioned  (59),  several  other  sub- 
stances are  required  to  build  up  the  plant  structure. 
These  are  almost  wholly  derived  from  the  soil,  through 
the  medium  of  the  water  absorbed  by  the  root -hairs 
(101).  They  must  all  be  dissolved  in  the  soil  water  or 
they  cannot  enter  the  plant,  for  they  must  pass  through 
the  cell-walls,  which  are  not  permeable  to  undissolved 
solid  matter. 

61.  The  Elements  regarded  as  Essential  in  the  Eood  of 
Plants  are  carbon,  hydrogen,  oxygen,  nitrogen,  potassium, 
calcium,  magnesium,  phosphorus,  iron,  chlorin  and  sul- 
fur.    Some  other  elements  that  do  not  appear  essential 
are  also  used  by  plants.     All  of  these  elements,  so  far  as 
they  serve  as  food,  are  absorbed  by  the  plant  in  the  con- 
diti6n'of  chemical  compounds,  as  water,  carbonic  acid 
and  various  nitrates,  sulfates,  etc. 

62.  The  Part  Played  by  the  Different  Elements.   Carbon 
is  the   chief    constituent  of  vegetable   substances   and 
forms  about  half  of  their  total  dry  weight.     Plants  obtain 
their  carbon  almost  wholly  from  the  air,  in  the  form  of 
carbonic  acid  gas,  which  is  a  compound  of  carbon  and 
oxygen.     The  leaves  absorb  and  decompose  this  gas,  re- 
taining the  carbon  and  giving  off  the  oxygen  (59).     Hy- 
drogen and  oxygen  are  obtained  by  the  decomposition  of 
water,  which  is  a  compound  of  hydrogen  and  oxygen. 
These  enter  into  the  construction  of  nearly  all  tissues. 
Nitrogen  is  one  of  the  constituents  of  protoplasm  (13). 
Most  plants  depend  upon  soluble  nitrates  in  the  soil  for 
their  nitrogen  supply,  but  those  of  the  natural  order  to- 


1 11 


The  Plantlet.  45 

which  the  clover  belongs  *  are  able  to  appropriate  nitro- 
gen from  the  air  (260).  Phosphorus  and  sulfur  assist 
in  the  formation  of  albuminous  substances;  potassium. 
assists  in  assimilation  (59);  calcium  f  and  magnesium, 
while  uniformly  present,  seem  to  be  only  incidentally 
useful.  Iron  is  essential  to  the  formation  of  chlorophyll 
(58). 

Of  all  the  materials  obtained  by  plants  from  the  soil, 
but  three,  aside  from  water,  viz.,  nitrogen,  phosphorus 
and  potassium  (254)  are  needed  in  such  quantities  that 
the  plants  are  likely  to  exhaust  the  supply,  so  long  as 
water  is  not  deficient. 

-  63.  Water  is  Necessary  to  Growth.  An  adequate  sup- 
ply of  water  is  the  most  important  condition  for  the  well- 
being  of  plants,  since  it  not  only  serves  in  nutrition,  but 
is  the  vehicle  by  which  all  other  food  constituents  are 
distributed  throughout  the  plant.  Comparatively  few 
soils  are  so  poor  as  to  be  incapable  of  producing  good 
crops  when  sufficiently  supplied  with  water,  while  the 
richest  soils  are  unproductive  when  inadequately  supplied 
with  it.  Much  of  the  benefit  of  manuring  undoubtedly 
conies  from  the  increased  capacity  it  gives  the  soil  for 
holding  and  transmitting  water  (93). 

The  supplying  of  food  material  is  not  the  only  office 
performed  by  water  in  the  plant.  The  unfolding  and 
expansion  of  the  plantlet  is  largely  due  to  a  strong  ab- 
sorptive power  for  water  possessed  by  the  protoplasm 
within  the  cells.  This  force  causes  all  living  parts  of 

*  Leguminosse. 

f  Lime,  which  is  a  compound  of  calcium,  appears  to  be  essential  to  the 
fruiting  of  some  plants,  as  the  peanut,  while  detrimental  to  the  fruiting 
of  others,  as  the  cranberry  and  huckleberry. 


46  Principles  of  Plant  Culture. 

plants  to  be  constantly  saturated  with,  water.  Indeed,  it 
distends  the  elastic  cell-walls  with  water  until  they  are 
like  minute  inflated  bladders.  The  pressure  thus  set  up 
aids  in  unfolding  the  different  parts  from  their  snug  rest- 
ing place  within  the  seed- case  and  enables  the  plantlet 
to  stand  erect,  Growth  by  cell  division,  it  is  true,  be- 
gins rather  early  in  the  germination  process,  but  this 
cannot  take  place  unless  the  cells  are  first  distended  with 
water  (29).  A  sufficient  amount  of  water  is  absolutely 
necessary,  therefore,  to  growth  in  plants.  Foliage  wilts 
in  dry  weather  because  the  roots  are  unable  to  supply 
enough  water  to  properly  distend  the  cells;  growth  is 
impossible  in  plants  of  which  the  foliage  is  wilted. 
When  the  water  supply  is  abun'dant,  on  the  other  hand, 
and  the  absorptive  power  of  the  roots  is  stimulated  by  a 
warm  soil  (102),  the  pressure  within  the  cells  often  be- 
comes sufficient  to  force  w^ater  from  the  edges  and  tips 
of  leaves.  The  drops  of  water  that  so  often  sparkle  on 
foliage  in  the  sunlight  of  summer  mornings,  commonly 
mistaken  for  dew,  are  usually  excreted  from  the  leaves. 
In  young  plants  of  the  caladium,  water  is  sometimes 
ejected  from  the  leaf-tips  with  considerable  force. 

The  water  of  plants  is  almost  wholly  absorbed  by  the 

0 

root-hairs  (101),  the  leaves  having  no  power  to  take  up 
water,  even  in  wet  weather.  The  water  of  plants,  with 
its  dissolved  constituents,  is  commonly  called  sap,  except 
in  fruits,  where  it  is  usually  called  juice. 

64.  How  Food  Materials  are  Distributed  through  the 
plant.  If  we  drop  a  bit  of  aniline  blue  into  a  glass  of 
clear  water,  it  will  not  retain  its  form  and  size,  but  infi- 
nitely small  particles  will  become  detached  and  move 


The  Plantld.  47 

about  to  all  parts  of  the  water  in  which  it  dissolves. 
This  movement  will  not  stop  until  the  bit  has  entirely 
disappeared,  and  until  every  part  of  the  water  contains 
exactly  as  much  of  the  aniline  blue  as  every  other  part. 
This  equal  distribution  of  the  soluble  material  takes 
place  in  response  to  the  law  of  diffusion,  that  tends  to 
cause  any  soluble  substance  to  become  equally  distributed 
throughout  the  liquid  in  which  it  is  placed.  The  liquid 
in  the  meantime  may  remain  stationary.  The  process 
would  be  the  same  if  we  were  to  put  in  a  very  small 
quantity  of  each  of  several  soluble  substances  at  the  same 
time.  The  movements  of  one  of  these  substances  would 
not  interfere  much  with  those  of  the  others. 

If  we  could  remove  some  of  the  dissolved  aniline  blue 
from  the  water  in  one  part  of  the  glass,  it  would  follow 
that  the  dissolved  aniline  blue  would  move  from  the 
other  parts  toward  this  point,  and  if  this  removal  were 
continuous,  slow  currents  would  move  in  this  direction 
from  all  other  parts  of  the  glass. 

We  may  now  understand  how  the  materials  from  which 
the  plant  is  built  up  are  distributed  to  its  different  parts. 
The  water  absorbed  by  the  root-hairs  (101)  is  not  chem- 
ically pure,  but  holds  in  solution  small  quantities  of  vari- 
ous soluble  matters  contained  by  the  soil,  some  of  which 
are  used  by  the  plant  in  growth.  As  these  useful  mat- 
ters are  removed  from  the  water  of  the  cells,  to  be 
formed  into  food  (59),  the  supply  is  replenished  from 
the  soil,  not  through  any  power  of  selection  possessed  by 
the  ptant,  but  in  accordance  with  the  law  of  diffusion. 
In  like  manner,  the  food  formed  by  the  chlorophyll  (59) 
finds  its  way  to  the  growing  parts.  Soluble  matters  not 


48 


Principles  of  Plant  Culture. 


used  by  the  plant  are  not  taken  in  to  the  same  extent  as 
those  that  are  needed,  because  their  equal  distribution  is 
less  disturbed. 

The  distribution  of  soluble  matter  in  the  plant  is  also 
promoted  by  transpiration  (75). 

SECTION  IT.  THE  INNER  STRUCTURE  or  THE  PLANTLET 

Thus  far,  we  have  considered  the  plantlet  mainly  from 
the  outside.  Before  going  farther,  it  is  well  to  learn  also 
something  of  its  inner  structure.  We  have  seen  that  all 
parts  of  the  plant  are  made  up  of  cells  (12)  and  that 
these  cells  differ  in  form  and  office  in  the  different  parts. 
The  cells  of  the  leaf,  for  example,  are  different  in  shape 
and  in  the  use  they  serve  to  the  plant,  from  those  of  the 
stem,  flower  or  fruit. 

65.  The    Epidermis    (ep'-i- 
EP-  der'-mis).     The  plant  is  cov- 
ered  by    a   thin,    translucent 
skin  that  extends  over  the  en- 
tire surface  of  the  leaves,  stem 
and  root,  called  the  epidermis 
(Fig.  17  Ep.).     This  skin  is 
formed    of    comparatively 
thick  walled  cells  and  serves 
to  protect  the  more   delicate 
Ep  parts   within.     It    may   be 
FIG.  IT.  showing  section  through  readily  withdrawn    in    some 

leaf  of  Oldenburgh  apple.    Ep.  ep-   plants,  as  from  the   leaves   of 
idermis;  Pal.  palisade  cells;    J in- 
tercellular spaces.   Highly  magni-  the  liveforever  *  and  echev- 
fied.    See  also  Figs.  13  and  20. 


Pal. 


er  ja  |  ail(J  young  Stems  of  the 

plum.     The   exposed   surface  of  the   epidermis  of  the 
leaves,  fruit  and  young  stems  of  many  plants  is  trans- 

*  Sedu m  teleph ium.  f  Cotyledon . 


The  Inner  Structure  of  the  Plantlet.  49 

formed  into  a  layer  that  is  more  or  less  impervious  to 
water,  called  the  cuticle  (cu'-ti-cle),  which  serves  to  re- 
strict evaporation  (75).  To  further  protect  the  parts,  a 
layer  of  wax  (bloom)  is  sometimes  secreted  upon  the 
outside  of  the  cuticle,  as  in  the  fruit  of  many  varieties 
of  the  plum  and  grape. 

Root-hairs  (101)  and  the  hairs  and  bristles  on  the 
stems  and  leaves  of  many  plants  are  cells  of  the  epider- 
mis elongated  outward.  The  epidermis  must  not  be  con- 
founded with  the  bark.  It  is  replaced  by  bark  in  the 
older  stems  of  woody  perennial  plants. 

To  give  further  strength  to  the  upper  surface  of  the 
leaf,  the  first  two  or  three  tiers  of  cells  beneath  the  epi- 
dermis on  the  upper  side  are  usually  placed  endwise, 
(palisade  cells,  Figs.  17,  15  and  3).  The  hardier  varie- 
ties of  apple,  as  the  Oldenburgh  (Duchess),  have  more 
numerous  and  more  crowded  palisade  cells  than  less 
hardy  varieties.  Compare  the  palisade  cells  of  a  leaf 
of  the  Oldenburgh  apple  (Fig.  17),  with  those  of  Fig. 
3,  which  shows  a  section  from  a  leaf  of  a  tender  variety 
of  apple. 

66.  Stomata  (stom'-a-ta).  Minute  openings  through 
the  epidermis  occur  in  the  leaves  and  young  stems  of 
land  plants,  connecting  intercellular  spaces  (I,  Fig.  17) 
with  the  external  air.  These  openings  are  each  bounded 
by  a  pair  of  crescent- shaped  guard-cells,  called  stomata, 
(singular,  stoma,  (sto'-ma),  (Figs.  18  and  19,  St).  They 
are  chiefly  found  on  the  lower  side  of  leaves,  and  are  ex- 
tremely numerous,  but  are  too  small  to  be  seen  without 
the  microscope.  An  average  apple  leaf  has  been  com- 
puted to  contain  about  150,000  stomata  to  the  square 
inch  on  its  lower  surface. 


50 


Principles  of  Plant  Culture. 


The  guard-cells  are  delicately-balanced  valves  which 
are  extremely  sensitive  to  external  influences.     They  are 

open  in  strong 
light,  but  usu- 
ally closed  in 
darkness  and 
w  hen  the 
leaves  are  wet. 
The  water  es- 
caping from 
leaves  (75), 
and  the  car- 
bonic acid  en- 
tering them 
(62)  mostly 

FIG.  18.    Showing  stomata  (st.)  on  leaf  of  the  garden  paSS     through 
beet.  Moderately  magnified.  (After  Fank  and  Tschirch). 
See  also  Figs.  15, 19  and  22.  the    Stomata. 

The  slightly-raised  spots  or  dots  on  the  smooth  bark  of 
the  young  shoots  of  many  woody  plants,  (lenticels  (len'-ti- 
cels)),  serve  a  similar  purpose  to  the  stomata. 

67.  The  Growing 
Point.  At  the  tip  of 
the  stem  and  just  be- 
hind the  tip  of  the 
root,  is  a  group  of 
cells  forming  the  so- 
called  growing  point. 
These  cells  divide 
very  rapidly  during 
the  growing  season, 
and  from  them  all 


FIG.  19.    Showing  stomato  (st.)  on  leaf  of 
Oldenburgh  apple.    Highly  magnified. 


other  kinds  of  cells  are  evolved. 


The  Inner  Structure  of  the  Plantlet. 


51 


68.  The  Vascular  (vas'-cu-lar)  Bundles.  While  the 
plantlet  remains  within  the  seed-case,  it  consists  largely 
of  cells  more  or  less  cubical  or  globular  in  outline.  But 
germination  scarcely  commences  before  some  of  the  cells 
begin  to  increase  greatly  in  length  without  a  correspond- 
ing increase  in  thickness,  f  These 
elongated  cells  form  in  groups  or 
bundles  (vascular  bundles)  that  extend 
lengthwise  through  the  stem  and  roots, 
and  since  the  individual  cells  overlap 
and  are  in  intimate  contact,  they  form 
threads  or  fibres.  These  fibres  serve 
the  double  purpose  of  giving  strength 
to  the  plant  and  conducting  water, 
with  its  dissolved  food  materials,  to 
the  different  parts.  By  the  absorp- 
tion of  the  ends  of  some  of  the  cells, 
tubes  (ducts)  of  very  considerable 
length  are  formed.  In  other  cells  of 

FIG.  20.  Prosenchyma 

cells  from  stem  of  rye.  vascular  bundles,  the  walls  are  much 
'an  d  thickened  and  strengthened  by  woody 
These  groups  or  bundles  of 


deposits. 

fibres  and  ducts  divide  and  subdivide  in  the  leaves, 
forming  the  so-called  veins  and  veinlets.  In  the  roots 
they  divide  in  a  similar  manner,  extending  lengthwise 
through  all  the  branches  and  branchlets. 

Fig.  21  shows  a  cross-section  of  a  vascular  bundle  of 
the  sunflower. 

The  threads  in  the  stalk  of  Indian  corn  and  the  leaf- 


*  Also  called  flbro-vascular  bundles. 

t  Cells  of  the  former  class  are  called  Parenchyma  (pa-ren'-chy-ma),  and 
those  of  the  latter  class  prosenchyma  (pro-sen'-chy-ma)  (Fig.  20).  Fig.  17 
shows  parenchyma  cells  from  the  apple  leaf. 


-52  Principles  of  Plant  Culture. 

stem  of  the  plantain  *  furnish  examples  of  well-defined 
vascular  bundles;  in  most  stems  the  vascular  bundles 

are  less  clearly  de- 
fined. In  woody 
stems  they  are 
closely  crowded, 
which  gives  the 
wood  its  firm  text- 
ure. In  some  woody 
plants,  as  the  grape 
and  the  elder  f  a 
cylinder  extending 
through  the  center 

FIG.  21.    Showing  cross-section  of  a  vascular      f  f}         ,  .      ~ 

-bundle  of  the  sunflower,  (Helianthus  animus).    C 
Highly    magnified.    (After   Prantl).    See   also    from     V  a  S  C  U  1  a  r 

bundles,     forming 

the  pith.  The  young  stems  of  asparagus,  the  ball  of  the 
kohl-rabi  and  the  roots  of  turnip  are  ."stringy"  when 
the  cells  of  their  vascular  bundles  become  thickened  by 
the  deposit  of  woody  material  in  them. 

69.  The  Cambium  (cam'-bi-uni)  Layer.  In  most  plants 
having  two  or  more  cotyledons  (46),  a  layer  of  cells  in 
a  state  of  division  (15)  exists  between  the  bark  and  the 
wood,  called  the  cambium  or  cambium  layer  (Fig.  22).  It 
is  in  this  layer  that  growth  in  diameter  of  the  stem  occurs 
(71).  The  bark  of  plants  having  the  cambium  layer 
separates  readily  from  the  wood  at  times  when  growth  is 
rapid,  because  the  walls  of  the  newly-formed  cambium 
cells  are  extremely  thin  and  tender.  The  slimy  surface 
of  growing  wood,  whence  the  bark  has  just  been  re- 
moved, is  due  to  the  protoplasm  from  the  ruptured  cam- 


*  Plantago.  f  Sambucus. 


The  Inner  Structure  of  the  Plantlet.  53 

bium  cells.  In  plants  having  more  than  one  cotyledon, 
the  cambium  line  is  usually  readily  discerned  in  cross- 
sections  of  the  stem  —  though  it  is  rather  more  distinct 
and  the  bark  is  more  readily  separable  in  woody  than  in 
herbaceous*  stems.  In  the  latter,  the  part  within  the 

GU  at 


e—  - 


;CW -V 


FIG.  22.  Showing  transverse  section  of  corner  of  a  bean  stem  (Vicia 
faba).  C  cambium  layer;  e  epidermis;  Cu  cuticle;  St  stoma.  The  dark, 
oval-shaped  spots,  extending  both  sides  of  the  cambium  layer  are  the  vas- 
cular bundles;  W  wood  cells  of  the  vascular  bundles.  Moderately  mag- 
nified. (After  Potter). 

cambium  line  corresponds  to  the  wood  of  woody  stems, 
and  that  outside  of  it  corresponds  to  the  bark. 

70.  Portions  of  Cambium  from  different  plants  may 
Unite  by  Growth.  If  a  section  of  cambium  from  one  part 
of  a  plant  is  closely  applied  to  the  cambium  of  another 
part  of  the  same  plant  or  of  another  closely -related  plant, 

*  Herbaceous  stems  are  those  that  do  not  have  the  hard,  firm  texture 
of  wood,  as  of  the  potato,  rhubarb  etc. 


54  Principles  of  Plant  Culture. 

the  two  portions  of  cambium  may  unite  by  growth,  a 
fact  of  great  importance  in  horticulture  since  it  renders 
grafting  possible  (383).  Plants  having  no  cambium  layer 
(71)  cannot  be  grafted,  because  their  steins  have  no 
layer  of  dividing  cells  —  the  only  cells  that  unite  by 
growth. 

71.  How  Stems  Increase  in  Diameter.  There  is  no 
cambium  layer  in  plants  having  but  one  cotyledon  (46 ), 
of  which  Indian  corn,  the  grasses  and  the  palms  are  ex- 
amples. In  such  plants  there  is  no  clear  separation  be- 
tween bark  and  wood;  the  stem  enlarges  for  a  time  by 
growth  throughout  its  whole  diameter,  after  which  it 
ceases  to  expand. 

In  plants  having  two  or  more  cotyledons,  however,  ad- 
ditions to  the  bark  cells  are  constantly  being  made  dur- 
ing the  growing  season  on  the  outside  of  the  cambium 
layer,  as  are  additions  to  the  wood  cells  on  the  inside  of  it 
(Fig.  22).  It  follows  that  growth  of  the  bark  takes 
place  on  its  inner  surface  and  growth  of  the  wood  takes 
place  on  its  outer  surface.  This  explains  the  vertically - 
furrowed  appearance  of  the  bark  of  old  trees  which  is 
being  constantly  split  during  the  growing  season  by  the 
forming  layer  within.  It  also  explains  the  ringed  ap- 
pearance of  a  cross- section  of  a  woody  stem.  A  new 
ring  of  wood  is  formed  each  season  on  the  outside  of  that 
previously  formed,  and  the  line  separating  the  rings 
marks  the  point  where  growth  in  autumn  ceased  and 
was  renewed  the  following  spring.  The  age  of  a  given 
part  of  the  stem  of  a  woody  plant  is  approximately  in- 
dicated by  the  number  of  its  wood  rings.* 

*  More  than  one  wood  ring  is  sometimes  formed  in  a  season.  If  growth 
ceases  during  the  summer  from  severe  drought  or  other  cause,  and  is  re- 
newed the  same  season,  an  extra  ring  is  formed. 


The  Inner  Structure  of  the  Plantlet. 


55 


72.  The  Vital  Part  of  Woody  Stems  in  plants  having 
more  than  omk  cotyledon  (40)  is  limited  to  a  rather  thin 

layer  of  bark  and  wood,  of 
which  the  cambium  (69)  forms 
the  center.  The  cells  of  the 
so-called  heart- wood  and  those 
of  the  dry  and  furrowed  outer 
bark,  have  lost  their  proto- 
plasm, and  hence  are  no  longer 
alive,  though  they  serve  a 
useful  purpose  in  adding 
strength  and  protection  to  the 
vital  layer.  The  heart- wood 
of  a  tree  may  largely  decay 
without  materially  interfering 
with  the  vital  processes  (Fig. 
23). 

73.  The  Healing  of  Wounds. 
Cambium  cells  exposed  to  the 
air  by  partial  or  complete  re- 
moval of  the  bark,  soon  per- 
ish, as  a  rule,  hence  growth 
ceases  in  a  part  of  the  stem 
thus  injured.  The  uninjured 
cambium  cells  on  the  borders 
of  the  wound  may,  however, 
FIG.  ^Tluve~pop)iar  tree  with  by  division  (15),  form  a  cush- 
hoiiow  trunk,  showing  to  what  jon  of  new  material  that  grad- 

extent  the  heart-wood  may  decay 

without  destroying  the  life  of  a  ually  extends  over  the  injured 
tree-  part.  A  new  cambium  layer 

may  thus  be  formed  over  the  wound  if  it  be  not  too 
large,  so  that  growth  of  the  stem  may  be  resumed  at  this 
place.  The  same  process  occurs  when  a  branch  is  cut  off 


56 


Principles  of  Plant  Culture. 


near  its  union  with  the  stem.  The  wound,  if  not  too 
large,  is  "healed"  by  new  growth  from  the  adjacent, 
uninjured  cambium  cells  (Fig.  24).  In  planted  cuttings, 

the  uninjured   cam- 

bium   cells    at    the 

base  form  the  callus 

(cal'-lus)    by    con- 

tinued   division. 

(Fig.  25). 
Exposure  of   the 

bark  to  undue  heat 

or  cold  may  destroy 

the    cambium,  caus- 

ing sunscald  (186). 
In  periods  of  very 


off  a  branch  (A).  the     CaniblUUl     Cells  willow  cutting. 

are  unusually  active,  large  areas  of  bark,  even  extending 
clear  around  the  stem  and  as  deep  as  the  cambium  layer, 
may  sometimes  be  removed  from  trees  without  destroy- 
ing their  life,  provided  the  recently-formed  wood  layer  is 
not  injured  (71).  In  this  case,  the  outer  cells  of  the  thin 
layer  of  cambium  that  remains  on  the  surface  of  the 
wood  promptly  change  to  bark  cells,  hence  a  new  bark 
layer  forms  over  the  exposed  surface  the  same  season. 

Several  successive  crops  of  bark  are  sometimes  removed 
from  the  trunk  of  the  cork  oak,*  but  in  this  case,  the 
cambium  layer  is  usually  not  injured. 


*  Quercus  suber. 


The  Water  of  Plants  and  its  Movements.  57 

SECTION  V.     THE  WATER  OF  PLANTS  AND  ITS  MOVE- 
MENTS 

74.  Plants  Contain  Large  Amounts  of  Water.     We  have 
seen  that  the  cell-walls  of  living  plants  are  constantly 
saturated  with  water  (63),  and  that  the  cells  of  the  grow- 
ing parts  are  always  more  or  less  distended  with  it.   The 
proportion  of  water  contained  in  living  plants  is  gener- 
ally very  large.     In  the  root  of  the  turnip  and  in  some 
fruits,  it  may  exceed  ninety  per  cent  of  the  whole  weight. 
It  is  greatest  in  young  plants  and  in  the  younger  and 
growing  parts  of  older  plants.     The  proportion  of  water 
is  not  constant  in  the  same  plants,  but  varies  somewhat 
with  the  water  content  of  the  soil  and  with  meteorologi- 
cal conditions. 

75.  Transpiration    (traiis-pi-ra'-tion).     The   water   of 
plants  passes  off  more  or  less  rapidly  from  parts  exposed 
to  the  air  —  usually  as  an  invisible  vapor.     This  invisi- 
ble escape  of  water  from  plants  is  called  transpiration.   It 
is  mainly  due  to  evaporation  of  water  from  the  plant, 
the  same  as  takes  place  from  other  moist  material.     But 
fluctuations  occur  in  the  amount  of  transpiration  from 
living  plants  that  do  not  occur  in  dead  organic  material 
under  similar  conditions.     For  example,  transpiration  is 
more  rapid  in  light  than  in  darkness,  because  the  stomata 
(66)  are  open  in  the  light  and  thus  facilitate  the  escape 
of  water  from  the  intercellular  spaces.     Plants  poorly 
supplied  with  nourishment  transpire  more  freely  under 
the   same    conditions  than  those   well   supplied.     The 
amount  of  transpiration  varies  greatly  in  different  plants 

and  depends  upon  the  leaf  surface,  the  nature  of  the  epi- 
4 


58  Principles  of  Plant  Culture. 

dennis  and  cuticle  (65),  the  number  of  stomata  (66)  etc. 
Some  plants,  as  purslane,  the  sedums,  cacti  etc.,  have 
special  water-storing  tissue,  from  which  transpiration  is 
extremely  slow. 

Experiments  indicate  that  the  transpiration  from  most 
leaves  is  between  one-third  and  one-sixth  as  much  as  the 
evaporation  from  an  equal  area  of  water.  When  we 
take  into  account  the  immense  leaf  surface  of  a  large 
tree,  it  is  evident  that  the  aggregate  transpiration  must 
be  very  great,  as  is  often  illustrated  by  the  dwarfing  in- 
fluence of  trees  upon  adjacent  crops  in  dry  weather  (Fig. 
26).  Transpiration  is  much  more  rapid  during  dry 


FIG.  26.  Showing  how  a  spruce  hedge  dwarfs  an  adjacent  corn  crop  in 
dry  weather. 

than  during  w,et  weather,  and  in  the  rare  atmosphere  of 
high  altitudes  than  in  the  denser  atmosphere  of  low 
lands. 

Excessive  transpiration,  as  occurs  in  very  dry  weather, 
is  detrimental  to  plants,  since  it  reduces  the  water  pres- 
sure within  the  cells  below  the  point  where  healthful 
growth  can  take  place  (63);  but  normal  transpiration, 
i.  e.,  not  sufficient  in  amount  to  interfere  with  healthful 
growth,  is  doubtless  beneficial,  since  it  aids  in  carrying 


The  Water  of  Plants  and  its  Movements.  59 

food  materials  from  the  soil  into  the  leaves  (59).  For 
this  reason,  plants  native  to  regions  having  a  rather  dry 
atmosphere,  do  not  thrive  in  greenhouses  unless  abund- 
ant ventilation  is  given  to  encourage  transpiration. 

76.  Trees  are   Detrimental  to  Crops  in  their  vicinity 
not  only  by  the  shade  they  cause,  but  also  by  their  ex- 
exhausting  effect  upon  the  soil  moisture  in  dry  weather. 
The  area  affected  by  a  group  of  trees  is  often  much 
larger  than  is  supposed.     The  illustration  on  page  58 
(Fig.  26)  shows  how  an  evergreen  hedge  may  restrict 
the  growth  of  corn  in  an  adjoining  field.     We  should 
not  infer  from  this,  however,  that  trees  are  on  the  whole 
detrimental   to   agriculture.     They   serve   many   useful 
purposes. 

Experimental  crops  intended  to  be  comparable  with 
^ach  other  should  not  be  planted  near  growing  trees. 

77.  The   Brittleness  of  Young    Plant  Tissues   depends 
upon  the  degree  of  water  pressure  within  the  cells.     Fo- 
liage is  usually  most  brittle  during  the  morning  and  least 
brittle  during  the  latter  part  of  the  day,  because  trans- 
piration is  most  active  during  the  warm  hours  of  the 
day.     Lettuce  and  other  salad  plants  are,  therefore,  apt 
to  be  most  crisp  and  tender  when  cut  in  the  morning. 
Tobacco,  in  which  breaking  of  the  leaves  is  detrimental, 
is  preferably  cut  in  the  afternoon.     Young  hoed  crops 
are  generally  less  injured  by  the  smoothing  harrow  in 
the  afternoon  than  in  the  morning,  and  grass  intended 
for  hay  usually  dries  soonest  when  cut  in  the  afternoon. 
Lawn  grass  generally  cuts  easier  in  the  morning  than  in 
the  afternoon. 

Slightly  withered  vegetables  may  have  their  crispness 
partially  restored  by  soaking  them  in  water  for  a  time. 


60  Principles  of  Plant  Culture. 

78.  The  Evaporation  Current.    Since  the  water  of  plants 
is  taken  in  from  the  soil  through  the  root-hairs  (101), 
and  escapes  more  or  less  rapidly  by  transpiration  (75), 
it  is  clear  that  in  leafy  plants  a  current  of  water  must 
pass  from  the  roots  through  the  stem  and  branches  into 
the  leaves,  and  that  the  rate  of  this  current  will  depend 
much  upon  the  rate  of  transpiration  from  the  foliage. 
When  the  soil  moisture  is  reduced  and  transpiration  is 
excessive,  this  upward  current  of  water  is  not  always 
sufficient  to  maintain  the  normal  pressure  within  the 
cells  (63),  hence  the  foliage  wilts,  or  the  leaves  roll  up, 
as  in  Indian  corn  and  some  other  plants  of  the  grass 
family.     This  current  passes  chiefly  through  the  younger 
vascular  bundles  (68),  which  in  trees  constitute  the  so- 
called  sap-wood,  since  the  cells  of  these  are  less  obstructed 
by  woody  deposits  than  those  of  other  tissues. 

The  physical  forces  that  cause  the  soil  water  to  rise  to 
the  tops  of  the  tallest  trees  are  not  well  understood,  but 
osmosis*  and  the  pull  produced  by  the  evaporation  of 
water  from  the  leaves,  play  important  parts. 

79.  The    Flow   of  Sap   in   Spring.     In   the   temperate 
zones,  evaporation  from  the  leafless  stems  of  deciduous 
trees  and  shrubs  nearly  ceases  during  winter.     The  por- 
tion of  the  roots  of  these  plants,  however,  that  lies  below 
the  frost  line,  continues  to  absorb  water,  which  gradu- 
ally accumulates  in  the  stems  and  branches.     On  the 
return  of  spring  weather,  the  rise  in  temperature  causes 

*  Osmosis  is  the  tendency  that  causes  two  liquids  of  different  densities 
to  mix  with  each  other  when  separated  by  a  permeable  membrane.  The 
less  dense  liquid  tends  to  flow  into  the  denser  one  with  a  force  correspond- 
ing to  the  difference  in  their  densities.  Cell  contents  are  denser  than  soil 
water,  hence  the  latter  tends  to  flow  into  the  cells,  and  thus  to  rise  in  the 
plant. 


The  Water  of  Plants  and  its  Movements.  61 

expansion  of  the  tissues  of  the  stem,  as  well  as  of  the  air 
and  water  within  it.  This  creates  so  much  pressure  in 
some  trees  and  shrubs  that  water  flows  freely  from 
wounds  in  the  wood,  bearing  with  it,  of  course,  the  ma- 
terials it  Jiolds  in  solution.  This  happens  when  we  tap 
a  sugar  maple  tree  in  spring.  Alternate  rise  and  fall  of 
temperature  increase  the  flow  of  sap,  because  with  each 
contraction,  new  supplies  of  water  or  air  are  drawn  into 
the  stem,  and  thus  the  pressure  is  maintained.  Sap 
ceases  to  flow  on  the  opening  of  the  buds,  because  trans- 
piration from  the  foliage  (75)  quickly  relieves  the  ab- 
normal pressure. 

The  popular  idea,  that  the  flow  of  sap  in  spring  is  due 
to  a  rapid  rise  of  water  through  the  stem  at  that  season, 
is  erroneous.  The  sap  is  really  rising  through  the  stem 
much  faster  in  midsummer  than  in  early  spring. 

80.  The  Current  of  Prepared  Food.  The  food  of  the 
protoplasm  in  the  different  parts  of  the  plant  is  prepared 
almost  wholly  in  the  leaves  (121).  We  know,  however, 
Hi  at  growth  occurs  in  the  stem  and  roots  as  well  as  in 
the  leaves.  It  is  clear,  therefore,  that  when  the  stem 
and  roots  are  growing,  a  movement  of  food  matter  must 
occur  from  the  leaves  into  these  organs.  This  movement 
may  be  demonstrated  by  a  simple  experiment.  If  a 
notch  deep  enough  to  pass  through  the  bark  and  a  little 
into  the  wood,  is  cut  into  the  stem  of  any  of  our  common 
woody  plants  during  spring  or  summer,  a  callus  or  cush- 
ion of  new  cells  (73)  will  soon  form  on  the  upper  side 
of  the  notch,  but  not  on  the  lower,  showing  that  the  ma- 
terial from  which  new  cells  are  formed  is  passing  down- 
ward. Close  examination  will  show  that  this  callus 


62  Principles  of  Plant  Culture. 

forms  just  outside  the  union  of  the  bark  and  wood.  In 
all  plants  having  more  than  one  cotyledon  (46),  this  cur- 
rent is  through  the  inner  layers  of  the  bark.  The  pre- 
pared food  matter  is  dissolved  in  the  water  that  saturates 
the  cell- walls,  and  passes  from  the  leaves  to  other  parts 
of  the  plant  by  diffusion  (64). 

81.  Killing  Trees  by  Girdling.     To  destroy  the  life  of  a 
tree  that  can  not  be  conveniently  removed,  we  girdle  it 
by  cutting  a  notch  about  the  trunk  beneath  the  lowest 
branch.     This  cuts  off  the  downward  food  current  and  so 
starves  the  protoplasm  of  the  roots.     If  the  notch  is 
made  after  the  leaves  have  expanded  in  spring,  and  ex- 
tends only  through  the   bark,  the   leaves  may  remain 
fresh   for   several  weeks,  for   the   transpiration   current 
passing    through    the    sap-wood    (78)    may    continue. 
Since  the   roots  receive  no  nourishment  however,  they 
will  soon  cease  to  grow  and  will  usually  die  from  starva- 
tion before  the  following  spring.     If  the  notch  is  cut 
deep  enough  to  reach  through  the  sap-wood,  thus  cutting 
off  both  the  ascending  and  descending  currents,  death  of 
the  tree  soon  follows. 

82.  Root  Starvation  may  occur  Without  Girdling.     In 
seasons  of  extreme  drought,  when  the  leaves  are  poorly 
supplied  with  crude  food  materials  from  the  soil,  the 
amount  of  prepared  food  may  be  so  meagre  that  the  food 
current  will  be  exhausted  before  it  reaches  the  roots.    In 
such  cases  the  roots  perish,  and  the  tree  is  found  dead 
the  following  spring.     This  most  frequently  occurs  with 
trees  on  poor  soil,  that  have  suffered  from  insect  attacks 
as  well  as  from  a  dearth  of  water.     It  often  occurs  also 
in  recently-transplanted  trees  that  fail  to  make  satisfac- 
tory growth  the  first  season. 


The  Water  of  Plants  and  its  Movements.  63 

83.  To  Destroy  the  most  persistent  Weeds  we  starve 
the  roots  by  preventing  all  leaf  growth  (339). 

84.  Restriction  of  the  Growth  Current  Promotes  Fruit- 
fulness  by  causing  an  accumulation  of  prepared  food  in 
the  stein  ,and  branches  (135  B). 

85.  The  Storage  of  Reserve  Food.     In  healthy  plants, 
food  is  usually  prepared  faster  than  it  is  consumed  by 
growth.    The  surplus  may  be  in  the  form  of  starch,  as  in 
the  potato  (Fig.  16),  wheat  and  sago;  sugar,  as  in  the 
sugar  cane,  sugar  maple  and  beet;   or  oil,  as  is  cotton 
seed,  flax  seed  and  rape.     Aside  from  the  seeds,  which 
are  always  stocked  with  reserve  food,  certain  plants  liv- 
ing more  than  one  year,  as  the  potato,  beet,  onion,  kohl- 
rabi etc.,  have  special  accumulations  of  food  in  certain 
parts,  and  the  parts  of  plants  that  contain  such  reserve 
food  are  most  valuable  as  food  for  man  or  animals.     The 
proportion  of  starch  stored  in  potato  tubers  is  not  con- 
stant, hence  the  food  value  of  different  samples  of  pota- 
toes may  vary  greatly.     In  woody  plants,  the   surplus 
food  is  more  evenly  distributed   through  the  different 
parts,  though  the  older  leaf -bear  ing  wood  is  usually  best 
supplied. 

86.  Plants  Use  their  Reserve  Food  in  the  production  of 
flowers  and  seeds  (135  A),  and  in  repairing  damages,  as 
the  healing  of  wounds  (73),  or  the  replacement  of  leaves 
destroyed  by  insects  or  otherwise.     Annual  plants  (337) 
expend  all  their  reserve  food  in  flower  and  seed  produc- 
tion and  then  perish  as  soon  as  the  seed  is  ripe.     Bien- 
nial plants  devote  the  first  season  of  their  life  to  storing 
an  abundant  food  supply,  which  is  expended  in  flower 
and  seed  production  the  second  year.     Our  seed  crops, 


64  Principles  of  Plant  Culture. 

as  oats,  corn,  peas  and  beans,  are  mostly  annuals;  our 
vegetables  other  than  seeds,  as  beets,  cabbage,  parsnips 
and  celery,  are  mostly  biennials.  Perennial  plants,  in 
normal  condition,  expend  only  a  part  of  their  reserve 
food  in  any  one  season  for  the  production  of  flowers  and 
seeds,  withholding  the  remainder  for  nourishment 
through  the  winter  and  to  develop  leaves  the  following 
spring.  The  reserve  food  in  dormant  cuttings  (358)  en- 
ables them  to  form  roots  and  expand  their  buds. 

SECTION  YI.     THE  BOOT  AND  THE  SOIL 

With  the  out-door  cultivator,  the  part  of  the  plant 
environment  that  lies  beneath  the  soil  surface  is  more 
under  control  than  the  part  that  lies  above  it.  He  can 
do  little  to  change  the  composition  or  temperature  of  the 
air  or  the  amount  of  sunlight;  he  may  do  much  to  influ- 
ence the  fertility,  the  texture,  the  drainage  and  the  aera- 
tion of  the  soil.  A  knowledge  of  the  roots  of  plants  and 
of  the  soil  in  which  they  grow  and  feed,  is  therefore,  of 
the  utmost  practical  importance. 

87.  The  Office  of  the  Root.     The  roots  of  land  plants 
serve  (a)  to  anchor  the  plant  in  the  soil,  enabling  the 
stem  or  stems  of  erect  species  to  grow  upright,  and  (b) 
to  supply  the  plant  with  water  with  its  dissolved  food 
materials  (63). 

88.  The  Root  Originates  in  the  Stem.    As  we  have  seen 
the  primary  root  develops  from  the  lower  or  u  root-end77 
of  the  hypocotyl  (45).     But  lateral  roots  may  develop 
freely  from  other  parts  of  the  stem.     If  we  examine  the 
base  of  the  stem  of  a  plant  of  Indian  corn  a  few  weeks 


The  Boot  and  the  Soil.  65 

after  planting,  we  may  see  that  the  main  roots  start 
above  the  point  at  which  the  stem  was  originally  attached 
to  the  seed;  and  if  we  pull  up  a  pumpkin  vine  or  an  un- 
trellised  tomato  plant  late  in  summer,  we  often  find  it 
rooted  from  the  stem  at  some  distance  from  the  original 
root.  Lateral  roots  originate  in  the  internal  tissues  of 
the  stem  or  root  and  not  close  to  the  surface,  as  do  buds 
(132). 

89.  Moisture  Excites  Root  Growth.     Eoots  develop,  as 
a  rule,  from  portions  of  the  stem  that  are  maintained  for 
a  certain  time  in  contact  with  abundant  moisture.     In 
the  pumpkin  vine  and  tomato  plant  above  mentioned, 
nearness  to  the  soil  furnishes  a  moist  atmosphere.     A 
corn-stalk  pegged  down  to  the  ground  for  some  distance 
will  usually  root  at  all  joints  of  the  stem  in  contact  with 
the  soil.     A  potato  plant  grown  under  a  bell -jar,  where 
the  air  is  nearly  saturated  with  water,  will  form  roots  at 
any  joint  of  the  stem.     In  parts  of  the  tropics  where  the 
air  is  very  moist,  certain  plants,  as  orchids  and  the  Ban- 
yan tree,  *  emit  roots  freely  from  the  stem  above  ground. 
Cuttings  (358)  and  layers  (349)  form  roots  because  they 
are  maintained  in  contact  with  abundant  moisture  and  at 
a  suitable  temperature.     Cuttings  of  some  plants,  as  the 
willow  and  nasturtium,  f  root  promptly  when  their  stems 
are  immersed  in  water. 

90.  Oxygen  is  Necessary  to  the  Life  of  Roots.     Since 
the  cells  of  newly-formed  roots  are  filled  with  proto- 
plasm, they  must  have  access  to  the  oxygen  of  the  air,  or 
they  can  neither  live  nor  g.row.     This  is  shown  by  a 
simple   experiment.     Boil   a   quantity  of  water  fifteen 

*  Ficus  Indica.  f  Tropceolum. 


66 


Principles  of  Plant  Culture. 


minutes  or  longer,  to  exhaust  it  of  free  oxygen,  and  then 
cool  it  quickly  by  setting  the  dish  containing  it  in  cold 
water.  Now  place  a  healthy  cutting  (358)  of  some 
plant  that  roots  freely  in  water,  as  willow,  nasturtium  or 
wandering  jew,*  in  each  of  two  tumblers.  Pour  a  part 
of  the  cool,  boiled  water  into  one  of  the  tumblers  and 
add  a  little  olive  oil  to  for.m  a  film  over  the  liquid  thus 
preventing  it  from  absorbing  more  air.  Then  agitate 
the  rest  of  the  water  vigorously  to  impregnate  it  again 
with  oxygen,  and  pour  some  of  this  into  the  second  tum- 
bler. Set  both  tumblers  in  a  light,  warm  place.  In  a 
few  days  roots  will  start  freely  from  the  slip  in  the  tum- 
bler in  which  the 
water  has  access  to 
the  air,  but  not  in  the 
other  (Fig.  27).  If 
now  the  rooted  cut- 
ting is  placed  in  oil- 
covered  water  that 
has  been  exhausted  of 
its  oxygen  by  boiling, 
the  roots  will  soon  die. 
The  copious  forma- 
tion of  root-hairs 
(101)  that  reach  out 
into  the  moist  atmos- 
phere of  t  h  e  s  e  e  d- 
tester  (39),  and  that 
so  often  fills  the  soil 

FIG.  27.    Slips  of  Tradescantia  in  water  con-  cavities  with    a    deli- 
taining  oxygen  (left  glass)  and  in  water  con- 
taining no  oxygen  (right  glass).  From  nature.  Cate,  COttOliy  dOWU,  IS- 

*  Tradescantia. 


The  Root  and  the  Soil.  67 

further  proof  that  roots  search  for  air  as  well  as  water. 
The  total  absence  of  live  rootlets  in  the  puddled  clods  of 
badly-tilled  fields  shows  that  roots  will  not  penetrate  soil 
from  which  the  air  has  been  expelled  by  undue  compres- 
sion while  wet.  Plants  in  over- watered  greenhouse  pots 
sometimes  send  rootlets  into  the  air  above  the  soil  to 
secure  the  oxygen  from  which  their  roots  have  been 
deprived. 

91.  The  Ideal  Soil  for  Land  Plants  must  contain  enough 
plant  food  and  water  to  fully  supply  the  plants,  and  yet 
be  so  porous  that  air  can  circulate  through  it  and  come 
in  contact  with  the  roots.     Each  particle  of  such  a  soil 
is  surrounded  by  a  thin  film  of  water,  while  between  the 
particles  are  spaces  connected  with  each  other,  and  filled 
with  moist  air  that  is  in  communication  with  the  air 
above  the  soil.     The  root-hairs  (101)  apply  themselves, 
intimately  to  the  wet  surfaces  of  the  soil  particles,  or 
reach  out  into  cavities  filled  with  saturated  air,  and  are 
thus  able  to  draw  in  the  well-aerated  soil  water,  with  its 
dissolved  food  constituents,  in  sufficient  quantity  to  re- 
store the  loss  from  transpiration  (75)  and  to  distend  the 
newly-formed  cells  (63). 

92.  The  Soil  is  a  Scene  of  Constant  Changes.   The  part 
of  the  soil  in  which  the  roots  of  plants  grow  is  the  field 
of  most  potent  vital  and  chemical  activities.     The  dead 
remains  of  plants  and  animals  it  chances  to  contain  are 
undergoing  decomposition  during  the  warm  season,  by 
serving  as  the  feeding  ground  of  myriads  of  microscopic 
plants  (bacteria).      Through  their  agency  nitric  acid, 
which  supplies  the  higher  plants  with  their  most  valu- 
able food  element  —  nitrogen  (255),  is  formed  in  the  soiL 


68  Principles  of  Plant  Culture. 

The  carbonic  acid  these  remains  took  from  the  air  during 
growth  is  also  set  free  to  slowly  disintegrate  the  mineral 
soil  constituents,  rendering  these  soluble  and  thus  avail- 
able as  plant  food.  In  winter,  the  frost  separates  the 
compacted  particles  of  clods,  making  the  latter  perme- 
able to  air  and  rootlets,  or  flakes  off  new  fragments  of 
rock,  thus  unlocking  new  supplies  of  mineral  fertility. 

93.  The  Importance  of  Organic  Matter  in  the  Soil.  Crops 
secure  a  large  part  of  their  nitrogen,  as  well  as  of  other 
food  substances,  from  dead  organic  matter,  i.  e.,  animal 
or  vegetable  materials.  The  application  of  such  matter 
to  the  soil  is,  therefore,  of  great  importance,  where  large 
crops  are  expected.  Stable  and  barn -yard  manure,  the 
offal  from  slaughter-houses,  tanneries,  breweries  etc.,  are 
all  valuable  for  this  purpose,  when  wisely  used,  ^ot 
only  does  organic  matter  in  the  soil  furnish  plant  food, 
but  while  in  a  partially  decomposed  state  (humus),  it 
renders  the  soil  porous  and  greatly  increases  its  water- 
holding  power. 

<^_  94.  The  Soil  Needs  Ventilation.  The  roots  of  growing 
plants  and  the  decomposition  of  organic  matter  in  the 
soil  tend  constantly  to  exhaust  the  latter  of  its  free  oxygen, 
and  to  replace  this  with  carbonic  acid,  which  is  not  used 
by  the  roots.  Hence,  without  some  interchange  between 
the  contents  *of  the  soil  cavities  and  the  atmosphere 
above,  the  roots  sooner  or  later  become  smothered  and 
perish.  In  sufficiently  porous  soil,  changes  in  tempera- 
ture and  in  atmospheric  pressure,  aided  by  wind  and  rain, 
furnish  the  needed  soil  ventilation,  but  in  poorly -drained 
soils,  and  soils  not  thoroughly  tilled,  the  roots  of  plants 
often  suffer  from  insufficient  oxygen.  A  puddled  crust 


The  Root  and  the  Soil.  69 

on  the  surface  of  clayey  soil,  due  to  the  compacting  influ- 
ence of  rain,  is  a  great  hindrance  to  its  ventilation. 
Earthworms  and  other  animals  that  burrow  in  the  soil 
aid  in  aerating  it. 

95.  Hotbeds  Require  Especial  Care  in  Ventilation  (365), 
since  they  usually  contain  large  quantities  of  decompos- 
ing  organic   matter    (manure),  which   rapidly  absorbs 
oxygen  from  the  soil,  replacing  it  with  carbonic  acid. 

96.  Drainage    Promotes   Soil   Aeration   by  forming  an 
outlet  for  the  surplus  water  that  would  otherwise  fill  the 
cavities.     Although  moisture  is  essential  to  root  growth, 
land  plants  do  not  prosper  with  their  roots  immersed  in 
water.     True,  most  plants  may  be  grown  in  "  water  cul- 
ture," i.  e.,  with  their  roots  from  germination  grown  in 
water  that  is  freely  exposed  to  the  air;  but  the  roots  of 
land  plants  soon  smother  for  want  of  free  oxygen  when 
the  soil  cavities  are  filled  with  water/ because  the  soil 
tends  to  prevent  the  water  witl  in  its  cavities  from  ab- 
sorbing air. 

97.  Potted  Plants  Require  Drainage  (412),  and  the  out- 
side of  the  pots  should  be   kept  clean,  to   admit   air 
through  their  walls.     Potting  soil  should  contain  suffi- 
cient sand  and  humus  (93),  so  that  it  does  not  readily 
become  puddled  by  watering  (31). 

98.  Potted  Plants  should  be  Watered  with  Care  (219). 
They  should  receive  sufficient  water  so  that  the  soil  par- 
ticles are  constantly  surrounded  with  a  film  of  water, 
but  not  so  much  that  the  soil  cavities  remain  filled. 

99.  How   the   Root-Tip   Penetrates   the   Soil.     Darwin 
made  the  interesting  discovery  that  the  root-tip,  in  ad- 
vancing through  the  soil,  does  not  move  in  a  straight 


70 


Principles  of  Plant  Culture. 


line,  but  has  an  oscillating  motion,  which  enables  it  to 
take  advantage  of  openings  between  the  soil  particles. 
The  force  with  which  the  root -tip  is  pushed  forward  was 
calculated  by  Darwin  to  be  at  least  a  quarter  of  a  pound 
in  some  cases,  while  the  increase  of  the  root  in  diameter 
may  exert  a  much  greater  force.  The  root-tip  is  pro- 
tected in  its  passage  through  the  soil  by  a  thimble- like 
covering  called  the  root-cap.* 

100.  Growth  of  Roots  in  Length.  Since  the  soil  offers 
more  or  less  resistance  to  the  growth  of  roots,  it  is  evi- 
dent that  the  roots  of  land  plants  can- 
not elongate  through  their  whole 
length  at  once.  On  the  contrary,  the 
part  that  increases  in  length  is  limited 
to  a  short  portion  just  behind  the 
root-tip.  Sachs  found  that  the  part 
of  the  rootlet  of  the  broad  bean  that 
increased  in  length  by  growth  scarcely 
exceeded  half  an  inch  long.  In  Fig. 
28,  the  parts  that  are  increasing  in 
length  are  considerably  shorter  than 
the  root-tips  (ET). 

101.  The  Root-Hairs  (Fig.  29  B.)  de- 
velop just  behind  the  elongating  part 
of  the  rootlet  and  are  present  in  nearly 
all  plants.  Their  object  is  to  absorb 

FIG.  28.  Roots  of  young  . 

wheat  plant.  The  parts  water,  with  the  food  materials  it  con- 
inciosed  in  sand  (RH)  tains.  The  root-hairs  greatly  increase 

are  surrounded  by  root-  . 

hairs.  RT,  root-tips;  e,  the  absorbing  surface  of  the  roots, 
older  parts  of  root.  One-  jus^  %$  leaves  increase  the  absorbing 

fourth  natural  size.  After 

Frank  and  Tschirch.        surface  of  the  plant  above  ground. 


*  The  root-cap  is  readily  seen  without  a  magnifying  glass  when  a  bean 
plant  is  grown  in  water. 


The  Eoot  and  the  Soil. 


71 


Each  root-hair  consists  of  a  single  elongated  cell  (Fig. 

30),  and  is  filled  with  protoplasm,  as  are  the  cells  in  other 
living  parts  of  the  plant  (13).  As  the  ex- 
tremity of  the  root  advances  through  the  soil 
lby  growth,  new  root-hairs  are  formed  in  front 
of  the  older  ones,  while  those  farthest  back  as 
rapidly  die  off,  so  that  only  a  short  portion  of 
a  rootlet  bears  root-hairs  at  any  one  time.  In 
Fig.  27  root-hairs  are  visible  in  the  left  glass, 
and  in  Fig.  6  they  may  be  seen  on  the  hypo- 
cotyl  of  some  of  the  germinating  corn  grains. 
In  Fig.  29A  and  in  Fig.  28  the  parts  of  the  root 
bearing  root- hairs  are  indicated  by  the  sand 
which  adheres  to  these  parts.  It  is  usually 
difficult  to  see  the  root-hairs  of  plants  grow- 

FiG.29.  Seed-  in&  ln  the  natural  Soil>  but  they  may  SOme- 
lings  of  turnip  times  be  discovered  with  the  help  of  a  pocket 
showing  root-  magnifying  glass  by  carefully  removing  the 

iiiiirs.     (Alter 

Frank  and  soil  particles  about  the  younger  roots,  when 

the    silky   network    of  root-hairs    may  be 

seen  filling  the  smaller  pores  of  the  soil  or  enveloping 

the  soil  particles.     Fig.  30  shows  a  magnified  root- hair 


FIG.  30.    Magnified  root-hair  of  wheat,  in  contact  with  soil  particles. 
(After  Sachs). 

of  the  wheat  plant,  closely  attached  to  some  particles  of 
soil.  The  root-hairs  are  able  to  take  up  water  freely, 
even  from  soil  that  does  not  appear  very  wet,  because 
each  soil  particle  is  enveloped  in  a  thin  layer  of  water 
(91).  Still  more  interesting  19  the  fact,  that  root-hairs 


72  Principles  of  Plant  Culture. 

are  able  to  dissolve  mineral  matters  in  the  soil,  by  their 
excretions  most  important  of  which  is  carbonic  acid, 
thus  permitting  the  plant  to  use  these  matters  as  food. 

102.  Root-Hairs  Absorb  Water  with  considerable  force. 
It  is  the  absorptive  power  of  the  root- hairs  that  causes 
water  (sap)  to  flow  so  freely  from  injured  stems  of  grape 
vines*  and  some  other  plants  in  spring,  and  from  wounds 
in  the  trunks  of  some  trees  in  summer.     This   force   is 
probably  due  to  the  absorptive  power  of  the  protoplasm 
in  the  very  active  young  root  cells.    It  is  affected  by  the 
temperature  of  the  soil  within  certain  limits,  lessening  as 
the  temperature  falls,  and  increasing  as  it  rises.     Sachs 
found  that  the  foliage  of  plants  of  tobacco  and  pumpkin 
drooped  when  the  temperature  of  the  soil  in  which  they 

"were  growing  was  reduced  much  below  55°  F.,  showing 
that  the  roots  did  not  absorb  enough  water  at  that 
temperature  to  compensate  for  the  loss  by  transpiration 
(75).  When  the  soil  is  warm,  on  the  other  hand,  the 
absorptive  power  of  roots  may  be  sufficient  to  force  water 
from  the  tips  of  leaves  during  cool  nights  when  tran- 
spiration is  slight  (63). 

103.  Only  the  Youngest  Parts  of  Roots  are  Active  in 
Absorption.     The  part  from  which  the  root-hairs  have 
perished  absorbs  little   water,  but  is  chiefly  useful  in 
giving  strength  to  the  plant  and  in  conducting  the  plant 
fluids.     The  absorbing  part   of  any   given   rootlet   is, 
therefore,    comparatively   short.        It  follows   that  the 
amount  of  nourishment  a  given  plant  can  receive  will 
depend  upon  the  number  of  its  root-tips.     Our  treatment 


*  Hales  found  the  absorbing  force  of  the  roots  of  a  grape  vine  equal  to 
the  weight  of  a  column  of  mercury  thirty-two  and  one-half  inches  high. 


The  Root  and  the  Soil.  73 

of  the  plant  should,  therefore,  be  aimed  at  promoting  the 
formation  of  root- tips.  In  other  words,  we  should  encour- 
age root  branching.  *  How  may  we  do  this  ? 

104.  The  Branching  of  Roots  in  land  plants  appears  to 
depend  much  upon  the  amount  of  free  oxygen  (31)  and 
available  plant  food  which  the  soil  contains,  so  long  as 
the  moisture  supply  is  sufficient.  In  cultivated  grounds 
having  a  compact  sub-soil  the  roots  of  annual  crops 
usually  branch  most  freely  just  at  the  bottom  of,  or  a 
little  below,  the  layer  of  soil  stirred  by  the  plow,  this 
being  the  point  at  which  the  supply  of  oxygen,  plant 
food  and  moisture  are  probably  best  suited  to  root 
growth.  As  the  depth  of  tillage  is  increased,  roots 
branch  freely  at  a  greater  depth.  Masses  of  decomposed 
manure  beneath  the  surface  of  the  soil  are  usually 
penetrated  through  and  through  with  finely-branched 
CA  roots:  and  fragments  of  bone  in 

•     *t 

the  soil  are  often  inclosed  in  a 
mat  of  delicate  rootlets.  These 
materials  furnish  plant  food  in 
abundance.  Roots  that  penetrate 
the  deeper  and  more  compact 
layers  of  soil,  on  the  other  hand, 
and  those  in  poor  and  dry  soils, 
are  usually  little  branched.  It  is 
_  clear,  therefore,  that  unless  a 

FIG.  31.  showing  how  root  Soil   is  well   aerated  (94)    by  a 

pruning    stimulates    root 

branching.  proper  system  of  tillage,  and  by 


*  Root  branches  must  not  be  confounded  with  root-hairs.    In  Fig.  28, 
branches  of  the  roots  appear  at  e.  e.  e.    The  branches  bear  root^hairs  when 
of  sufficient  length,  but  root-hairs  never  develop  into  branches. 
5 


74  Principles  of  Plant  Culture. 

draining  if  need  be,  and  unless  it  contains  abundant 
soluble  plant  food  in  the  aerated  part,  the  roots  of 
plants  growing  upon  it  will  not  branch  freely  and  hence 
the  plants  cannot  be  well  nourished. 

105.  Transplanting  (400)  and  Root  Pruning  (416) 
Stimulate  Root  Branching.  Removing  the  growing  points 
of  either  the  stem  or  root  (67)  stimulates  the  development 


FIG.  32.  Showing  effects  of  transplanting  on  root  growth  of  celery 
plants.  The  left  two  plants  were  transplanted  when  quite  small;  the 
right  two  were  not.  (After  Green.) 

of  other  growing  points  farther  back.  Transplanting  or 
root  pruning  accomplishes  this  in  the  case  of  roots  (Fig. 
31,  p.  73).  While  these  operations  may  not  often  increase 
the  total  number  of  root-tips,  and  hence  may  not  enable  the 
plant  to  take  up  a  greater  amount  of  nourishment,  they 
do  cause  the  development  of  a  more  compact  root  system, 
which  is  of  great  advantage  to  young  plants  grown  in 
the  seed-bed  or  nursery  for  subsequent  transplanting. 


The  Eoot  and  the  Soil.  75 

106.  Pricking  Off  Young  Seedlings,  i.  e.,  transplanting 
them  from  the  soil  in  which  they  grew  to  other  soil, 
where  they  have  more  room,  is  an  important  preparation 
for  their  final  transplanting.     They  should  receive  as 
good  care  after  pricking  off  as  before,  with  which  they  soon 
develop  many  new  rootlets  near  the  base  of  the  stem,  that 
need  be  little  injured  in  the  later  removal  (Fig.  32,  p.  74). 

107.  Nursery  Trees  are  Benefited  by  Transplanting  them 
once  or  twice  before  the  final  planting  out,  for  the  rea- 
sons named  above. 

108.  Root  Pruning  (416  k)  is  sometimes  employed  as  a 
substitute  for  transplanting,  and  is  especially  useful  to 
trees  that  form   few  branch   roots,  as  the  hickory  and 
walnut.     In  this  case,  the  tap  root  is  cut  off  a  few  inches 
below  the  surface  of  the  soil  the  year  before  transplanting. 

109.  The  Horizontal  Extent  of  Roots  is  usually  greater 
than  is  generally  supposed.     In  upright- growing  plants, 
the  area  occupied  by  the  roots,  as  a  rule,  exceeds  that 
covered  by  the  foliage,  while  in  spreading  and  trailing 
plants,  the  roots  are  probably  not  often  less  in  extent 
than  the  branches.     It  appears  from  the  observations 
recorded  that  even  in  such  plants  as  the  melon  and 
squash,  the  horizontal  extent  of  the  roots  usually  equals 
or  exceeds  that  of  the  runners.     As  the  diffusion  of  solu- 
ble matters  in  the  soil  water  is  probably  much  hindered 
by  the  soil  particles,  the  roots  of  plants  need  to  travel 
farther  after  food  than  do  the  branches,  which  develop 
in  a  freely  circulating  medium.     Especially  is  this  true 
of  plants  growing  in  poor  soil. 

110.  The  Depth  of  Roots  in  the  Soil.     It  appears  from 
the  observations  recorded  that  the  extreme  depth  reached 


76  Principles  of  Plant  Culture. 

by  roots  is  generally  less  than  their  greatest  horizontal 
extent.  The  distance  reached  by  the  deeper  roots  is 
probably  governed  largely  by  the  nature  of  the  subsoil 
and  the  depth  of  free  ground  water.  But  in  most  annual 
crops  a  comparatively  small  part  of  the  root  system  de- 
velops much  below  the  plow  line.  At  the  Geneva  Ex- 
periment Station  *  the  chief  root-feeding  ground  of  the 
field  and  garden  crops  grown  in  that  locality  appeared 
to  be  from  three  to  ten  inches  below  the  surface,  while 
that  of  crops  making  large  development  of  stem  and  foli- 
age during  summer,  as  Indian  corn,  sorghum,  tobacco 
and  the  Cucurbits,  appeared  to  be  shallower  than  in 
slower- growing  crops. 

A  portion  of  the  roots  of  many  crops  grow  very  near 
the  surface  of  the  ground.  Branches  from  the  main 
horizontal  roots  often  grow  upward  as  well  as  in  other 
directions.  At  the  Geneva  Experiment  Station,  numer- 
ous roots  of  sweet  corn  were  found  within  an  inch  of  the 
surface,  and  in  a  tall-growing  southern  corn,  roots  of  con- 
siderable size  started  at  a  depth  of  only  half  an  inch. 
The  main  root  of  a  Hubbard  squash  vine  was  traced  a 
distance  of  ten  feet,  in  which  its  depth  varied  from  two 
to  five  inches.  In  tobacco  fields,  the  rootlets  sometimes 
literally  protrude  from  the  surface  of  the  soil  in  warm,, 
wet  weather  (232). 

III.  The  Rate  of  Root  Growth  in  rapidly  developing 
plants  is  often  extremely  fast.  President  Clark,  formerly 
of  the  Massachusetts  Agricultural  College,  concluded 
from  very  careful  examinations  and  measurements  of  the 
roots  of  a  squash  vine  grown  under  glass,  that  rootlets 

*  See  Report  of  New  York  Agricultural  Experiment  Station,  1886,  p.  165- 


The  Root  and  the  Soil. 


11 


must  have  been  produced  at  the  rate  of  at  least  one 
thousand  feet  per  da^  during  the  latter  part  of  the  growth 
period. 

112.  Relation  of  Roots  to  Food  Supply.  In  the  extent 
of  ground  occupied,  root  growth  is  relatively  less  in 
moist  and  fertile  soils  than  in  poorer  and  drier  ones,  but 

the  roots  are  proportion- 
ally more  branched.  In 
wet  seasons,  a  given  plant 
has  less  extensive  root 
development  than  in 
drier  seasons,  because 
the  roots  may  then  se- 
cure the  needed  food  and 
water  from  a  smaller 
area.  Nursery  trees 
grown  on  fertile  soils 
have  a  more  compact 
root  system  than  those 
grown  on  poorer  soils. 

113.  Root  Tubercles. 
Plants  belonging  to  the 
natural  order  Legumi- 

Fio.88.    Young  clover  plant  showing    nOS<*      Oe-gU-mi-no'-S8B), 
tubercles  on  roots  (t).    (From  nature).        of  which  the  Clover,  pea 

and  bean  are  familiar  examples,  when  grown  in  ordinary 
soil  have  swellings  or  tubercles  on  their  roots  (Fig.  33). 
These  are  caused  by  micro-organisms,  probably  of  the 
class  known  as  bacteria,  and  are  of  special  interest,  be- 
cause the  organisms  producing  them  render  nitrogen  of 
the  air  available  as  plant  food.  Plants  have  no  power 
to  utilize  directly  the  free  nitrogen  of  the  air  (260). 


78 


Principles  of  Plant  Culture. 


SECTION  VII.     THE  STEM 

114.  As  the  root  develops  from  the  base  of  the 
hypocotyl,  the  plumule,  or  primary  shoot  (56),  develops 
from  the  other  end  and  becomes,  at  least  for  a  time,  the 
main  axis  or  stem  of  the  plant. 

1 15.  The  Stem  is, 
generally  speakiifg, 
the  part  of  the  plant 
that  supports  the 
leaves.  In  excep- 
tional cases,  as  in 
the  potato  (Fig. 34) 


part  oi  the  stem 
grows  beneath  the 
ground,  on  which 
the  leaves  usually 
do  not  develop  (un- 
derground stems); 
and  in  a  few  plants, 
as  in  some  cacti,  the 
stem  performs  the 
whole  office  o  f 
leaves.  The  stem 
may  be  strong 
enough  to  support 
its  own  weight,  as  in  trees  and  shrubs,  or  it  may  depend 
upon  other  objects  for  its  support,  as  in  vines. 

116.  Nodes  and  Internodes.  Unlike  the  root,  the  stem 
is  developed  in  successive  sections,  comparable  in  part 
to  the  stories  of  a  building.  Each  section  or  story 


FIG.  34.  Potato  plant.  U.  St.,  under- 
ground stems;  R,  roots.  The  tubers  are  the 
thickened  distal*  ends  of  the  underground 
stems.  Much  reduced.  (After  Frank  and 
Tschirch.) 


See  foot  note  on  page  79. 


The  Stem. 


consists  of  one  or  more  leaves,  attached  to  the  distal*  end 
of  a  portion  of  the  stem.  The  part  of  the  stem  to  which 
the  leaf  or  leaves  are  attached  is  called  a  node  and  the 
part  below  the  node,  or  in  the  stem  as  a  whole,  the  part 
between,  the  nodes,  is  called  an  internode. 

The  nodes  are -distinctly  marked 
in  the  younger  stems  of  most  plants 
by  a  slight  enlargement  or  by  leaf- 
scars,  if  the  leaves  have  fallen  (Fig. 
35).  The  nodes  are  centers  of  vital 
activity  and  are  the  points  at  which 
lateral  growing  points  (buds  (128)) 
are  normally  formed,  and  whence 
roots  usually  start  first  in  cuttings 
and  layers  (358,  349). 

117.  The  Stem  Lengthens  by  Elon- 
gation of  the  Internodes,  as  well  as 
by  the  formation  of  new  ones.  As 
the  internodes  soon  attain  their  ulti- 
mate length,  it  follows  that  the  stem 
lengthens  only  near  its  distal  end. 
An  internode  that  has  once  ceased 

FIG.  35.    Nodes  (N);   A,  of 

the  box  eider,  Negundo  acer-  elongating  does  not  usually  resume 


N— 


;  B,  of  the  wild  grape,  jt  hence  the  internodes  of  peren- 

Vitis  riparia. 

nial  plants  that  are  only  partially 

elongated  at  the  close  of  the  growing  season  in  general 
remain  undeveloped.  When  growth  is  resumed  in  spring, 
the  formation  of  a  comparatively  long  internode  beyond 
the  very  short  ones  of  autumn  usually  forms  a  percepti- 
ble ring  about  the  shoot,  which  enables  us  to  readily 

*  Distal  means  farthest  from  the  point  of  origin,  i.  e.,  the  point  at  which 
growth  started.  It  is  opposed  to  proximal,  which  means  nearest  the  point 
of  origin. 


80  Principles  of  Plant  Culture. 

locate  the  point  at  which  growth  started  in  spring  (Fig. 
36).  Indeed  we  can  often  determine  the  amount  of 
growth  that  took  place  during  the  preceding  season  or 
even  farther  back. 

118.  The  Ultimate  Length  of  the  Internodes  in  any  plant, 
or  any  part  of  a  plant,  depends  upon  the  rate  of  growth  — 
rapid  growth  producing  long  internodes,  and 
vice  versa.  In  the  same  species,  therefore,  the 
average  length  of  the  internodes  is  much  greater 
in  vigorous,  young  plants  than  in  old  ones;  in 
the  main,  central  shoot  than  in  the  branches,  and 
when  growth  is  well  started  in  spring  than  dur- 
ing its  decline  in  autumn.  The  diameter  of 
young  internodes  that  are  not  unduly  shaded  is 
generally  in  proportion  to  their  length,  hence 
rapidly-growing  shoots  are  usually  thicker  than 
slower-growing  ones.  We  can  judge  of  the  com- 
parative vigor  of  nursery  trees  by  observing  the 
length  and  diameter  of  the  internodes. 
union  o6f  ll9  The  Stem  Elongates  Fastest  just  behind 
new  and  the  growing  point  (67),  and  at  least  in  young 
older  wood  behind  the  primary  or  original 


growing  point  (56).  When  we  desire  to  check  growth 
of  the  stem,  therefore,  we  remove  the  terminal  growing 
point  by  pinching  (416  a). 

120.  Pinching  Stimulates  Branching  because  removing 
the  terminal  growing  point  stimulates  the  development 
of  other  growing  points  farther  back  (105). 


The  Leaves.  81 

SECTION  VIII.     THE  LEAVES 

We  have  seen  that  one  or  more  leaves  are  normally 
formed  at  each  node  of  the  stem  (116). 

121.  The  Function  of  Leaves  is  food  preparation  (59). 
Since  food  is  prepared  only  in  the  light,  the  cells  of 
leaves  are  in  most  plants  so  arranged  as  to  best  expose 
them  to  light,  i.  e.,  in  thin,  more  or  less  horizontal  plates, 
which  are  strengthened  and  at  the  same  time  supplied 
with  water  by  a  network  of  vascular  bundles  (68)  con- 
necting with  the  stem.     They  are  protected  by  the  epi- 
dermis (65),  but  have  access  to  air  through  the  stomata 
(66). 

Each  leaf,  like  the  stem  and  root,  is  developed  from 
one  or  more  growing  points  (67),  one  of  which  forms  the 
terminus  of  each  lobe  or  division  of  the  leaf.  Cell  divis- 
ion in  the  leaf  is  confined  to  the  near  vicinity  of  the 
growing  points,  hence  an  injury  to  the  older  part  of  the 
leaf  is  not  repaired  further  than  by  the  formation  of 
callus  (73)  over  the  wounded  parts. 

122.  The  Cultivator  Should  Provide  for  Normal  Leaf  De- 
velopment.    Since  the  protoplasm  of  the  plant  is  nour- 
ished by  prepared  food  (59),  and  since  food  preparation 
in  most  plants  takes  place  almost  wholly  in  the  leaves 
(121),  it  is  of  first  importance  that  the  plant  be  so  cared 
for  as  to  promote  normal   leaf  development.      Without 
this,  good    crops    are    impossible.    The    plants    must  be 
grown  far  enough  apart  so  as  not  to  unduly  shade  each 
other  5  insects  and  fungi  must  not  be  permitted  to  prey 
upon  them  when  it  is  possible  to  prevent  it;  and  the 
leaves  must  not  be  needlessly  removed  or  injured. 


82  Principles  of  Plant  Culture. 

123.  How  Far  Apart  Should   Plants  be  Grown?     When 
the  finest  developed  plants,  or  parts  of  plants,  as  fruits, 
flowers,  leaves.,  stems  or  roots  is  desired,  the  plants  should 
not  be  grown  so  near  together  as  to  interfere  with  each 
other7  s  leaf  or  root  development.     But  when  the  largest 
crop  from  a  given  area  is  of  more  importance  than  the 
development  of  the  individual  plant,  as  with  grain  crops, 
the  loss  from  a  limited  amount  of  shade  and  crowding 
will  be  more  than  made  up  by  the  increased  number  of 
plants.     In  this  case,  the  amount  of  crowding  that  will 
give  the  maximum  yield  will  depend  much  upon  the 
fertility  and  moisture  of  the  soil,  and  must  generally  be 
determined  by  experiment. 

124.  Stem  and  Root  Development  Depend  on  the  Number 
of  Leaves.     Since  the   vascular   bundles,   through  the 
formation  of  which  the  stem  and  root  increase  in  diame- 
ter, originate  in  the  leaves  (68),  the  size  and  firmness  of 
the  stem  and  the  root  depend  somewhat  upon  the  num- 
ber of  leaves  the  plant  bears.     The  more  leaves  it  has, 
the  more  solar  energy  it  can  transform  into  plant  tissue. 
The  stem  is  larger  beneath  a  vigorous  leafy  branch,  and 
if  cut  off  some  distance  above  a  branch,  the  part  thus 
deprived  of  its  foliage  ceases  to  grow,  unless  it  develops 
new  leaves.     Trees  growing  in  the  dense  forest,  where 
their  lower  branches  continually  perish  through  lack  of 
light,  have  tall,  but  very  slender  trunks,  and  their  wood 
is  soft  because  it  contains  comparatively  little  fibrous 
tissue,  while  other  trees  of  the  same  species,  in  the  full 
light  of  the  open  field,  through  the  large  amount  of  solar 
energy   absorbed  by   an   immense   number    of    leaves, 
develop    massive    trunks,    of   which   the  wood,    being 


The  Leaves.  83 

packed  with  fibrous  tissue,  is  much  stronger  than  that 
of  the  forest  tree. 

125.  The  Comparative  Size  of  Leaves  on  a  given  plant 
depends  much  on  the  water  supply  during  their  forma- 
tion.    The^  leaves  of  sap-sprouts  (224),  that  take   an 
undue  proportion  of  water,  are  usually  very  large,  and 
in  upright-growing  plants,  the  leaves  on  the  more  nearly 
vertical  shoots  are  usually  larger  than  those  on  the  hori- 
zontal ones.     The  more  vigorous  the  plant,  the  larger, 
as  a  rule,  are  its  leaves,  and  the  softer  is  its  woody  tissue. 

In  plants  grown  from  seed  to  secure  new  varieties, 
large  leaves  may  be  taken  as  evidence  of  superior  root 
development,  which  implies  capacity  to  endure  drought 
and,  therefore,  hardiness.  In  the  apple,  the  large-leafed 
varieties  are,  as  a  rule,  hardier  than  others,  probably 
because  their  vigorous  roots  supply  the  needed  water 
during  the  dry  season,  thus  enabling  the  tree  to  mature 
healthy  wood  and  buds  which  can  pass  severe  winters 
unharmed  (175). 

Crops  grown  for  their  leaves,  as  cabbage,  lettuce,  to- 
bacco etc. ,  are  especially  liable  to  be  curtailed  by  drought, 
and  hence  should  be  given  the  culture  that  best  promotes 
soil  moisture,  as  abundant  surface  tillage  and  liberal 
manuring  (232). 

126.  Leaves  are  usually  Short-Lived  because  they  be- 
come clogged  with  those  mineral  matters  taken  up  with 
the  soil  water  which  are  not  used  by  the  plant  (64)  and 
which  do  not  pass  off  in  transpiration  (75).     In  most 
annual  plants  (337),  the  older  leaves  become  useless  from 
this  clogging  and  die  before  the  stem  is  fully  developed, 
and  in  most  perennials  the  leaves  endure  but  a  single 


84  Principles  of  Plant  Culture. 

season.  In  the  so-called  evergreen  plants,  in  which  the 
leaves  are  usually  very  thick  and  are  often  well  protected 
against  evaporation  by  a  very  strongly  developed  cuticle 
(65),  the  leaves  rarely  live  more  than  a  few  years. 

127.  The  Manurial  Value  of  Leaves,  that  mature  on  the 
plant,  is  usually  small,  since  the  more  valuable  fertilizing 
materials  they  contain   pass   into  the  stem  before  the 
leaves  ripen  (171).     The  mineral  matters  contained  in 
largest  quantity  by  leaves  are  those  that  are  not  used  by 
the  plant,  but  have  been  deposited  within  them  during 
transpiration  (126). 

SECTION  IX.     THE  BUDS 

128.  The  Buds.     Each  tip  of  the  stem  (67)  is  in  most 
plants  protected  with  a  covering  of  rudimentary  leaves 

or  leaf -scales,  and  the  tip  with  its  leafy  or 
scaly  covering  constitutes  a  bud.  A  bud 
forming  the  apex  of  a  shoot  is  called  a  ter- 
minal bud;  one  at  the  junction  of  a  leaf  with 
the  stem  (axil)  is  called  an  axillary  or  lateral 
bud  (Fig.  35). 

Each  bud  generally  includes  one  terminal - 
,.„  —    and  several  axillary  growing  points.  Aside 
from     these,  which     in     the     stem     exist 
only  in  the  bud,  a  bud  is  simply  a  part  of 
the  stem  in  which  the  leaves  and  internodes 

FIG. 3^ Buds.  are  in  the  embryo  stage. 
L,  lateral  buds.       In  most  perennial  plants,  the  rudimen- 
<  After  Barry).        £a      leaves  that  form  near  the  terminus  of 


the  young  shoots  at  the  latter  end  of  the  growing  season 
are  changed  into  bud-scales,  which  serve  to  protect  the 
growing  points  within  from  excessive  moisture  and  sud- 


The  Buds.  85 

den  changes  in  temperature.  Axillary  buds  which  have 
not  yet  formed  leaves,  are  clothed  with  similar  scales. 
Buds  inclosed  with  scales  are  often  called  winter  buds.  To 
more  effectually  shut  out  water,  the  scales  are  coated  with 
a  waxy  or.  resinous  layer  in  some  plants,  as  the  horse- 
chestnut  and  balm  of  Gilead,  and  to  protect  them  from 
too  sudden  changes  of  temperature,  they  are  lined  in 
other  plants,  as  the  apple,  with  a  delicate  cottony  down.* 

129.  Nature  Provides  very   Early  for  the   Next  Year's 
Growth  in  perennial  plants.     With  the  expansion  of  each 
leaf,  a  tiny  bud  begins  to  form  at  its  axil,  destined  if 
need  be  to  become  a  branch  the  following  year.     Some- 
times, however,  especially  in  very  vigorous  shoots,  the 
embryo  buds  at  the  axils  of  the  earliest  formed  leaves 
remain  undeveloped.    The  more  rapid  the  growth  of  the 
shoot,  the  less  developed,  as  a  rule,  are  the  lateral  buds. 
Cions  (386)  and  cuttings  (358)  should  not,  therefore,  be 
taken  from  excessively  vigorous  shoots. 

130.  Branches  Develop  from  Lateral   Leaf-Buds  (132). 
In  trees  and  shrubs  (woody  perennials),  the  lateral  buds 
do  not  usually  push  into  growth  until  the  spring  after 
their   formation,    unless   the   terminal   bud   is   injured. 
Indeed,  they  may  never  push  into  growth.    Some  lateral 
leaf-buds,  especially  those  most  distant  from  the  terminal 
bud,  usually  remain  dormant,  through  want  of  light  or 
nutriment,  and  are  overgrown  by  the  enlarging  stem  the 
following  year.     Such  overgrown  buds,   stimulated  by 
destruction  or  injury  of  the  stem  above,  sometimes  push 
into  growth  years  after  their  formation. 

*  A  vertical  section  of  the  onion  bulb  may  be  used  as  a  magnified  illus- 
tration of  a  bud  as  it  appears  in  winter,  and  that  of  a  head  of  cabbage,  of 
a  bud  unfolding  in  spring. 


86  Principles  of  Plant  Culture. 

We  can  usually  decide  if  detached  dormant  shoots  of 
trees  and  shrubs,  as  cions  and  cuttings,  are  of  the 
preceding  year's  growth  or  older,  since,  as  a  rule,  only 
wood  formed  the  preceding  year  has  visible  undeveloped 
buds.* 

131.  Adventitious   (ad-ven-ti'-tious)  Buds.      Although 
buds  are  normally  formed  only  at  the  nodes  of  the  stem, 
they  may  under  the  stimulus  of  unusual  root  pressure 
(102)  be  formed  without  regard  to  nodes.    The  trunk  of 
a  vigorous  elm,  willow  or  horse-chestnut  tree,  cut  off 
early  in  the  season,  often  develops  a  multitude  of  buds 
from  the  thickened   cambium  (69)  at  the  top  of  the 
stump,  and  a  circle  of  shoots  often  spring  up  about  the 
base  of  a  tree  of  which  the  top  has  been  injured  by  over- 
pruning  or  severe  cold.  Such  buds  are  called  adventitious. 
It  is,  however,  often  difficult  or  impossible  to  distinguish 
between  adventitious  buds  and  those  that  have  been 
previously  overgrown  (130). 

The  roots  of  many  plants,  as  the  plum,  choke  cherry, 
raspberry  etc.,  develop  adventitious  buds  freely,  especi- 
ally when  injured,  a  fact  often  utilized  in  propagation 
by  root  cuttings  (376). 

132.  Leaf-Buds  and  Flower-Buds.     Buds  may  contain 
only  rudimentary  leaves,  or  they  may  contain  rudimen- 
tary flowers,  with  or  without  leaves.     The  former  are 
called  leaf-  or  wood-buds,  the  latter  flower-  or  fruit-buds. 
Flower-buds  are  modified  leaf-buds.      Both  originate  in 
the  cambium  layer  (69)  and  are  normally  located  at  the 
apex  of  the  stem  or  in  the  axil  of  a  leaf  (128-129). 

*  Exceptions  to  this  rule  are  not  uncommon  in  unthrifty  trees  and 
shrubs. 


The  Buds. 


87 


133.  Flower-Buds  are  often  Readily  Distinguished  from 
Leaf-Buds  by  location  and  appearance  the  same  season  in 
which  they  are  formed,  which  enables  the  fruit  grower 
to  anticipate  his  crop.  In  the  peach  and  apricot,  and  in 
many  varieties  of  plum,  a  flower-bud  is  normally  formed 
on  each  side  of  the  leaf- bud  in  the  young  shoots  of  bear- 
ing trees  (Fig.  38).  In  the  apple  and  pear,  the  flower- 
buds  are  less  definitely  located,  but  are  mostly  formed 
on  the  short,  thick,  wrinkled  and  crooked  branches  from 
wood  three  or  more  years  old  (fruit  spurs,  Figs. 
42  and  43).  In  some  fruits,  as  the  apple,  cherry 
and  peach,  the  flower-buds  are 
usually  thicker  and  more  rounded 


Fm.  38. 


FIG. 


FIG.  40. 


FIG.  41. 


FIG.  42. 


FIG.  38.  Flower-buds  of  Potlawattamie  plum,  Prunus  angustifolia. 
The  central  bud  of  each  group  is  a  leaf-bud. 

FIG.  39.  Fruiting  branch  of  European  plum,  Prunus  domestica.  B, 
young  wood.  A,  wood  of  preceding  year.  S,  fruit  spurs. 

FIG.  40.  Fruiting  branch  of  Morello  cherry,  Prunus ,  cerasus.  B, 
young  wood.  A,  wood  of  preceding  year.  F,  clusters  of  fruit-buds. 

FIG.  41.    Leaf-buds  of  the  apple. 

FIG.  42.    Fruit-bud  of  apple-(F). 

All  are  reduced  one-half.    (Figs.  39,  40,  41  and  42  are  after  Barry). 


Principles  of  Plant  Culture. 


than  the  leaf -buds,  especially  toward  spring.  Close  and 
persistent  observation  will  enable  the  horticulturist  to 
early  distinguish  the  flower-buds  in  many  of  his  perennial 
plants. 

In  the  apple  and  pear,  the  buds  on  the  so-called  fruit- 
spurs  are  not  necessarily  flower-buds,  but  some  seasons 
all  are  leaf- buds.  How  early  in  the  life  of  the  bud  its 
character  is  fixed,  or  if  flower-buds  ever  change  to  leaf- 
buds  before  expanding,  does  not  appear  to  be  known. 
The  fact  that  leafy  shoots  sometimes 
grow  out  of  the  center  of  flowers, 
and  that  petals  (143)  are  sometimes 


FIG.  44.    Fruit  spur  of  the  pear.    Reduced 
one-half.    (After  Barry). 


FIG.  43.  Fruit  spurs  of  developed  as  leaves,  suggest  that 
the  apple.  A,  points  at  such  a  change  may  occur. 

which  apples  were  detach- 
ed the  preceding  year ;  w,       In  the  grape,  flowers  appear  at 

wrinkles   marking  points    th     firgt  two    three  Qr  four  nodes  of 

at  which  fruit  and  leaves 

were  detached  in  previous    the   young    shoots    that    gTOW    from 

Haardy).K<  *  stems  formed  the  preceding  season 

(canes}  and  the  shoot  continues  to  grow  beyond  the 
flowers.  The  raspberry,  blackberry  and  dewberry  bloom 
like  the  grape,  except  that  the  flowers  form  the  end  of 
shoots.  In  the  strawberry,  the  terminal  bud  of  the 


The  Buds.  89 

preceding  year's  growth  flowers  in  early  spring.  In 
these  plants,  therefore,  the  flower-buds  are  inclosed  by 
the  same  bud  scales  that  inclose  the  leaf -.buds,  hence  it  is " 
more  difficult  to  foresee  the  number  of  flowers  than  in 
the  tree  fruits.  A  knowledge  of  the  location  of  the 
flower- buds  is  very  important  in  pruning  plants  grown 
for  their  flowers  or  fruits  (416). 

134.  The  Comparative  Vigor  of  Leaf-Buds  on  a  given 
shoot  depends  somewhat  upon  their  location  and  the 
length  and  diameter  of  the  internodes.     The  terminal 
bud,  when  uninjured,  is  usually  the  most  vigorous  one, 
and  the  vigor  of  the  buds,  as  a  rule,  diminishes  as  we 
recede  from  the  terminal  bud.     On  a  given  plant,  the 
buds  are  usually  less  vigorous  on  shoots  having  very 
long  and  thick  internodes,  i.  e.,  the  shoots  that  grew 
very  rapidly  (118),  than  on  shoots  with  internodes  of 
average  length  and  thickness  (129).    The  more  vigorous 
buds  are   often  tenderer   than  the  less  vigorous  ones, 
since  they  are  usually  farther  developed  the  season  in 
which  they  are  formed. 

Cions  (386)  or  cuttings  (358),  of  dormant  wood,  should 
be  made  from  shoots  having  internodes  of  average  length 
and  thickness  and  with  plump,  well- matured  buds. 

In  the  potato  tuber,  which  is  the  thickened  terminus 
of  an  underground  stem  (Fig.  34),  the  most  vigorous 
shoot  comes  from  the  terminal  bud  (the  so-called  seed- 
end),  hence  rejecting  this  part  of  the  tuber  in  planting, 
as  has  often  been  recommended,  is  detrimental  to  the 
crop. 

135.  Conditions  Affecting  the  Formation  of  Flower-Buds. 
The  majority  of  cultivated  plants  are  grown  either  for 


90  Principles  of  Plant  Culture. 

their  flowers  or  the  product  of  their  flowers,  i.  e.,  fruit 
or  seed.  But  the  flower  is  not  an  essential  part  of  the 
plant,  and  instead  of  contributing  to  its  welfare,  as  do 
the  leaves  and  roots,  it  actually  consumes  a  part  of  the 
plant's  reserve  food  (140).  As  might  be  expected,  there- 
fore, perennial  plants  do  not  always  produce  an  annual 
crop  of  flowers,  even  when  well  developed  in  other  direc- 
tions, hence  the  grower  is  often  disappointed.  Since 
flowers  can  only  come  from  flower- buds,  a  knowledge  of 
the  laws  that  govern  the  formation  of  these  would  often 
be  valuable  to  the  cultivator.  Unfortunately,  this  sub- 
ject has  received  less  attention  than  is  due  to  it.  Two 
principles  may  be  cited,  however,  which  if  they  do  not 
explain  all  phenomena  connected  with  the  formation  of 
flower- buds,  are  of  sufficient  general  application  to  have 
great  economic  value,  viz: 

A  —  Plants  form  flower-buds  only  when  they  contain  re- 
serve food  (85). 

B  —  A  water  supply  insufficient  for  rapid  growth  may  suf- 
Jicefor  abundant  food  formation  (59). 

In  support  of  the  first  of  these  propositions,  we  men- 
tion: (a)  Rapidly-growing  plants  rarely  form  many 
flower- buds  because  the  food  is  used  up  in  growth  as  fast 
.as  formed,  (b)  Checking  such  rapid  growth,  by  remov- 
ing the  growing  points  of  the  stem  or  root  (67),  or  by 
"withholding  water,  results  in  an  accumulation  of  food 
and  is  often  followed  by  an  abundant  formation  of  flower- 
buds,  (c)  Obstructing  the  root  ward  current  of  prepared 
food  (80),  as  by  "ringing"  (416 g)  causes  an  accumula- 
tion of  food  above  the  obstruction  and  is  often  followed 
by  the  formation  of  flower-buds  in  that  part. 


The  Buds.  91 

In  support  of  the  second  proposition  we  mention: 
(a)  Florists  often  bring  their  plants  into  bloom  at  a  de-, 
sired  time  by  withholding  water,  (b)  The  flower-buds 
of  most  out- door  plants  are  formed  during  the  drier  part 
of  summer,*  when  a  restricted  water  supply  prevents 
rapid  growth,  but  when  abundant  sunlight  and  fully- 
expanded  foliage  favor  food  formation  (59). 

We  may  infer,  therefore,  that  treatment  that  favors  the 
accumulation  of  reserve  food  promotes  the  formation  of 
flower-buds,  a  proposition  that  is  borne  out  by  the  exper- 
ience of  practical  cultivators. 

136.  How  can  we  Promote  the  Accumulation  of  Reserve 
Food?  Three  general  principles  may  be  cited: 

A  —  Provide  for  abundant  food  formation  by  giving  suf- 
ficient light  and  air  and  by  protecting  the  foliage  from 
attacks  of  insects  and  fungi  (Chap.  Ill,  Section  VII). 

B  —  Provide  sufficient  plant  food  in  the  soil  to  satisfy  all 
requirements  of  food  formation  (Chap.  Ill,  Section  VI). 

C  —  Provide  for  a  moderate  check  to  growth  after  the 
proper  amount  of  growth  has  been  secured. 

In  the  greenhouse  where  conditions  are  under  control, 
these  principles  are  readily  followed,  and  the  skilled 
florist  rarely  fails  to  secure  bloom  at  the  proper  time. 
He  gives  the  desired  check  to  growth  by  permitting  the 
roots  to  become  densely  matted  in  the  pot  (pot-bound), 
by  withholding  water,  or  by  pinching  the  tips  of  the 
more  vigorous  shoots.  With  out-door  perennial  plants, 
as  fruit  trees,  the  problem  is  more  difficult,  since  condi- 
tions are  less  under  control  than  with  plants  under  glass, 

*  Plants  that  live  over  winter  and  bloom  in  spring,  as  the  apple,  straw- 
berry etc.,  form  their  flower-buds  the  preceding  season. 


92  Principles  of  Plant  Culture. 

but  the  principles  just  cited  should  always  be  kept  in 
mind  and  carried  out  so  far  as  possible. 

We  can  give  sufficient  light  and  air  by  planting  the 
trees  a  sufficient  distance  apart  (123)  and  by  proper 
pruning  (Chap.  IV,  Section  III). 

If  the  soil  is  properly  drained,  the  natural  depletion  of 
soil  water  about  midsummer  will  usually  give  the  needed 
Check  to  growth.  In  wet  seasons,  the  drying  of  the  soil 
may  be  promoted  by  stopping  cultivation  before  midsum- 
mer and  sowing  a  crop  that  will  increase  evaporation 
from  the  soil,  as  oats,  clover  or  buckwheat. 

137.  Pinching  Promotes    Flowering    (416).     In   certain 
cases,  as  with  seedling  trees  of  which  we  would  early 
know  the  quality  of  the  fruit,  we  may  give  an  abnormal 
check  to  growth  by  pinching  the  tips  of  the  young  shoots 
or  by  root  pruning  (416k).     These  operations  should  be 
performed  early  in  summer,  before  the  period  of  flower- 
bud  formation,  and  if  the  tree  is  not  too  young,  flowers 
and  fruit  may  be  expected  the  following  season.    Frequent 
transplanting  of  young  trees  acts  like  root  pruning,  especi- 
ally if  the  tap-root  is  severed.     Such  harsh  measures, 
however,  while   they  promote   early  fruiting,  doubtless 
tend  to  shorten  the  life  of  trees. 

138.  Ringing    (416  g)    often    Causes   the    Formation  of 
Flower-Buds  in  otherwise  barren  trees,  by  obstructing  the 
rootward  current  of  prepared  food.     Twisting  a  small 
wire   about   the   branch,  violently  twisting  the   branch 
itself,  or  simple  bending  and  fastening  it  in  an  unnatural 
position,  answers  the  same  purpose.     But  these  devices 
probably  weaken  the  tree  and  shorten  its  life  by  robbing 
the  roots  of  their  normal  food  supply  and  are  excusable 


The  Flower.  93 

only  in  special  cases,  as  with  seedling  trees.  It  is  gener- 
ally a  reproach  to  the  care  or  knowledge  of  the  cultiva- 
tor, if  his  trees  of  bearing  age  cannot  form  flower-buds 
without  such  choking. 

Fruit  trees  grafted  on  slightly  uncongenial  stocks  some- 
times flower  and  fruit  more  freely  for  a  time  than  when 
growing  on  their  own  roots,  because  the  imperfect  union 
of  cion  and  stock  (383)  forms  an  obstruction  to  the  root- 
ward  food- current. 

SECTION  X.     THE  FLOWER 

139.  The  Flower  is  the  developed  and  expanded  flower- 
bud  (132).     Its  office  is  to  provide  for  the  formation  of 
new  plants  of  its  kind  (reproduction,  16).     Some  plants, 
as  the  quack  grass,  *  Canada  thistle  f  and  horseradish  J 
multiply  freely  in  nature  without  the  aid  of  flowers,  and 
nearly  all  plants  may  be  multiplied  in  culture  by  other 
means,  but  in  most  of  the  higher  plants,  the  flower  is  the 
natural  organ  of  reproduction,  and  the  only  organ  devoted 
solely  to  this  end. 

140.  Flowers  Tend  to  Exhaust  the  Plant,  since  they  are 
formed  from  the  food  prepared  by  the  leaves.    But  since 
flower-buds  are  not  usually  formed  until  the  needs  of 
growth  are  provided  for  (135A),  the  normal  production 
of  flowers  does  not  injure  the  plant.     In  certain  cases, 
however,  as  in  plants  weakened  by  recent  transplanting 
or  in  cuttings  (358),  flower-buds  should  be  removed  as 
soon  as  discovered,  to  prevent  their  exhaustive  influence. 

141.  The  Parts  of  the  Flower.     The  complete  flower  is 
composed  of  four  different  parts  or  organs.    A  knowledge 

*  Agropyrum  repens.         f  Cnious  arvensis.         I  Nasturtium  Armoracia. 


;94  Principles  of  Plant  Culture. 

of  these  parts  is  of  great  importance  to  the  botanist  in 
determining  species,  and  also  to  the  plant  breeder  who 
would  practice  cross-pollination  (152,  440),  hence  we 
need  to  consider  them  in  detail.  The  cherry  blossom, 
of  which  a  vertical  section  appears  in  Fig.  45,  will  serve 
as  our  first  example. 

142.  The  Calyx  (ca'-lyx).     Beginning  at  the  bottom, 
the  part  marked  C  in  the  figure,  is  called  the  calyx.    This 
is  green  in  the  normal  cherry  flower.     In  some  plants, 
as  the  flax,  the  calyx  is  composed  of  several  distinct, 

more  or  less  leaf- 
like  parts,  each  of 
which  is  called  a 
sepal  (se'pal).  I  n 
the  cherry  blossom, 
the  sepals  are 
united  nearly  to  the 
top.  The  calyx  is 

FIG.  45.    Section  of  cherry  blossom.    C  calyx;    Usually    green,    but 
Cor.  corolla;  S  stamens.  jn    the    tulip    and 

some  other  flowers  it  is  of  another  color.  In  the  apple 
and  pear,  the  calyx  becomes  a  part  of  the  fruit,  and  its 
'points  are  visible  in  the  depression  opposite  the  stem. 

143.  The  Corolla  (co-rol'-la).    The  more  spreading  part 
:of  the  cherry  blossom,  which  is  normally  white  (Cor.r 
Fig.    45)    constitutes  the    corolla.     In  the   cherry,  the 
corolla  consists  of  fiVe  distinct  parts,  only  three  of  which 
appear  in  the  figure,  called  petals  (pet'-als).     In  many 
plants,  as  the  pumpkin  and  morning  glory,  the  petals  are 
united.     In  other  plants  they  are  united  a  part  of  the 
way  to  the  top.     The  corolla  is  usually  of  some  other 
color  than  green. 


The  Flower.  95 

144.  The  Stamens  (sta'-mens).     Inside  the  corolla  is  a 
group  of  slender  organs  (S  S,  Fig.  45)   called  stamens. 
Each  stamen  consists  of  three  parts,  viz.,  the  long  and 
slender  portion,  connected  with  the  calyx  below,  called 
the  filament  (nT-a-ment);  the  swollen  part  at  the  top, 
called  the  anther  (an'-ther);  and  the  yellow  dust,  found 
upon  or  within  the  anther,  called  ihe  pollen  (pol'-len). 
Each  grain  of  pollen  is  a  single  cell,  which   if  fertile 
(153)  contains  living  protoplasm.     The  pollen  is  set  free 
at  maturity. 

145.  The  Pistil  (pis' -til).     The  column- like  part  in  the 
center  of  the  flower  is  called  the  pistil.     This  also  con- 
sists of  three  principal  parts,  viz.,  the  enlarged  flattened 
summit,  called    the  stigma  (stig'-ma);   the   egg-shaped 
base,  called  the  ovary  (o'-va-ry);  and  the  slender  part 
connecting  the   two,  the  style.     The   ovary   contains  a 
smaller,  egg-shaped  part,  called  the  ovule  (o'-vule),  which 
when  developed  becomes  the  seed.     Many  flowers  have 
more  than  one  pistil,  and  many  ovaries  contain  more 
than  one  ovule. 

Recapitulating,  the  parts  of  the  flower  are,  in  the  or- 
der we  have  considered  them: 

a  —  The    calyx;   when    divided,  the   parts  are  called 


b  —  The  corolla;  when  divided,  the  parts  are  called 

petals. 
c  —  The  stamens;  the  parts  are  the  filament,  anther  and 

pollen. 
d  —  The  pistil  or  pistils;  the  parts  are  the  stigma,  ovary 

and  style. 

The  ovary  contains  the  ovule  or  ovules. 


96 


Principles  of  Plant  Culture. 


146.  The  Parts  of  the  Flower  Vary  in  Form  in  different 
species.     In  the  pea  flower  (Fig.   46)  the  five  petals, 

shown  separate- 
ly in  Fig.  47, 
are  not  only 
quite  unlike  the 
petals  of  the 
cherry  flower, 
but,  as  appears, 
they  are  unlike 

FIG.  46.    Flower  of  the  pea,  Pisum  sativum.  (After  -•       ,-•  m^ 

Baillon).  eacn  otner. 

FIG.  47.    The  same  dissected,  showing  variation  stamens  (Fig.  48 
in  form  of  the  petals.    (After  Figuier). 


FIG. 


FIG.  47. 


til  (Fig.  49)  of  the  pea  are  also  quite  different  in  form 
from  those  of  the  cherry.  The  variety  of  form  in  the 
parts  of  the  flowers  of  different  species  is  almost  infinite. 

147.  Certain  Parts  of  the  Flower  are  often  Wanting.   The 
flowers  of  the  maple  have  no  corolla;  those  of  the  willow 
have  neither  calyx  nor  corolla; 

certain  flowers  of  the  pump- 
kin, Indian  corn  and  many 
other  plants  have  no  stamens, 
while  other  flowers  of  the 
same  species  have  no  pistils 
(154).  In  many  varieties  of 
the  American  plums*  the  pis- 
til is  often  wanting. 

148.  Composite    (coni-pos'- 
ite)  Flowers  t  are  made  up  of 

FIG.  48.     -        FIG.  49. 

several  individual  flowers  in  FIG.  48.  stamens  (st)  and  pistil 
the  same  flower-head.  The  of  the  pea,  PI*M,,«  *«//™>H. 

FIG.  49.   Pistil  of    same   alone. 
SUn-flower      (Fig.     50)      IS     a      ( After  Baillon). 

*  Prunus  Americana,  P.  angustifolia,  P,  hortulano. 

f  The  plants  having  composite  flowers  form  an  extensive  family  in 
botany,  called  Compositce. 


The  Flower. 


97 


familiar  example  of  a   composite  flower.     One   of  the, 
separate  flowers  is  shown  in  Fig.  51.     At  the  outer  edge 

of  the  flower- head, 
is  a  row  of  individ- 
ual flowers,  each  of 
which  has  a  long, 
yellow,  petal-like 
appendage  (Fig. 
52),  called  a  ray. 
The  flowers  bearing 
rays  are  called  ray- 
flowers.  Some  com- 

FIG.  50.  Cross-section  of  flower-head  of  sun-  pOSlte  flowers  a  S 
flower,  Helianthus  annuus.  Reduced.  The  flor-  £Q^  tansv*  are  with- 
ets  appear  closely  crowded  in  the  center  of  the 

head.  out  ray-flowers. 

149.  The  Flowers  of  the  Grass  Family -I-  to  which  the 
cereals  belong,  as  well  as  corn,  sorghum,  sugar  cane  etc. , 
are  quite  different  from  those  of  most  other  plants.  In 
this  family,  the  flowers  are  arranged  in  little  groups, 
each  of  which  is  called  a  spike- 
let.  What  we  call  a  head  of 
wheat  is  made  up  of  a  number 
of  spikelets,  one  of  which  is 
shown  in  Fig.  53.  Fig.  54 
shows 'the  spikelet  dissected. 
The  two  scale-like  parts  at  the 
base,  g.  g.,  are  called  glumes. 
The  similar  pair  above,  tipped 
with  a  bristle  (the  awn  or 
beard)  are  called  the  lower  or  outer  pales  or  palets  (pa'- 
lets)  or  flowering  glumes  —  to  distinguish  them  from  the 

*  Tanacetum  vulgare. 
f  Graminece* 


FIG.  51. 
FIG.  51. 
flower. 
FIG.  52. 


FIG.  52. 
Enlarged  floret  of  sun- 

Ray-flower  of  same. 


98 


Principles  of  Plant  Culture. 


smaller  and  more  delicate  upper  or  inner  palets  which 
are  just  above  and  inclosed  within  the  outer  palets. 
Between- the  outer  and  inner  palets  are  the  stamens  and 
pistils,  shown  separately  in  Fig.  55. 


,,  -  -  sv~ 

&. 

FIG.  53.  FIG.  54.  FIG.  55. 

Fig.  53.    Spikelet  of  wheat;  st,  stamens.  (After  La  Maout  and  Decaisne) , 
Fig.  54.    The  same  dissected;    x,  axis  of  spikelet;  g,  glumes;  bn  b2r 

outer  pales;  Blf  B2,  flowers  displaced  from  the  axis  of  outer  pales;  p  sr 

inner  pales;  a,  anthers;  f,  ovary.    (After  Prantl). 

Fig.  55.    Flower  of  wheat,  enlarged;  st,  stamens;   p,  pistil;  o,  ovary, 

(After  La  Maout  and  Decaisne). 

150.  Fecundation  (fec'-un-da'-tion)  is  the  union  of  the 
male  and  female  cell  by  which  the  new  plantlet  is  formed.  * 
The  ovule  produces  within  itself  a  female  cell  which 
may  be  fecundated  by  the  male  cell  produced  by  the 
pollen  (144).     This  fecundated  cell  then  grows  to  form 
a  young  plant  —  the  embryo  (56),  and  the  parts  of  the 
ovule  develop  about  it,  the  whole  forming  the  perfect 
seed.     Unless  the   ovule   is  fecundated,  the  seed  very 
rarely  develops.     A  flower  that  contains  no  pistil  and 
hence  no  ovule,  can  of  course  produce  no  seed. 

151.  Pollination  (pol-lin-a'-tion),  is  the  access  of  pollen 
{144)  to  the  stigma  (145)  — the  first  step  in  the  process 

*  The  term  fertilization  (fer-til-i-za'-tion),  that  has  been  commonly  used 
for  this  process,  tends  to  confusion,  because  this  term  is  also  applied  to 
the  addition  of  plant  food  to  the  soil. 


The  Flower.  99 

of  fecundation.  During  a  certain  period,  the  surface  of 
the  stigma  is  moistioned  by  the  secretion  of  a  viscid 
liquid,  to  which  the  pollen  grains  readily  adhere.  Fer- 
tile pollen  grains,*  alighting  on  the  stigina  of  sufficiently 
near-related  plants  during  this  period,  undergo  a  process 
comparable  to  germination,  in  which  a  slender  projection 
from  the  pollen  cell  penetrates  the  stigma,  passes  length- 
wise through  the  center  of  the  style  and  enters  the  ovule, 
where  fecundation  occurs. 

Pollination  is  not  necessarily  followed  by  fecundation. 
In  young  plants,  and  in  older  plants  that  are  lacking  in 
vigor  (9),  flowers  often  fail  to  produce  seed  or  fruit,  even 
when  pistil  and  stamens  appear  to  be  normally  devel- 
oped, and  pollination  occurs. 

In  some  flowers,  as  in  the  pea,  the  stigma  is  brought 
into  direct  contact  with  the  pollen  by  the  elongation  of 
the  style,  but  in  most  plants  the  pollen  must  be  trans- 
ferred to  the  stigma  by  some  outside  influence,  as  by  in- 
sects, the  wind,  or  gravity.  Most  flowers  which  have  a 
showy  corolla  or  calyx,  or  secrete  nectar,  or  yield  a  fra- 
grant perfume,  depend  largely  upon  the  visits  of  pollen- 
loving  or  nectar-loving  insects  for  pollination.  The 
showy  parts  and  the  perfume  serve  as  signboards  to- 
direct  the  wandering  insects  to  the  flowers.  Pollination 
is  favored  by  a  warm,  dry  atmosphere. 

152.  Cross-Pollination  occurs  when  the  stigma  receives 
pollen  from  a  different  plant,  especially  from  a  plant  of 
a  different  variety  or  species  (21).  The  fecundation 
resulting  constitutes  a  cross  or  hybrid,  as  the  case  may  be 

*  Fertile  pollen  is  pollen  that  is  capable  of  fecundating  female  cells  of 
its  own  species. 


100  Principles  of  Plant  Culture. 

(23).     Cross- poll ination  is  often  performed   artificially 
(440). 

Close-  or  self-pollination  occurs  when  the  stigina  receives 
pollen  from  its  own  flower  or  plant. 

153.  Cross-Pollination    is    Advantageous   in   plants,   as 
Darwin's  careful  experiments  have  shown.     The  seeds 
formed  are  usually  more  numerous  and  larger  and  make 
more  vigorous  plants  than  with  close-pollination.     Es- 
pecially is  this  true  when  the  parent  plants  have  been 
subjected  to  different  growth  conditions  in  previous  gen- 
erations.    Nature    favors    cross-pollination    in  perfect- 
flowered  plants  by  numerous  adaptations  tending  to  pre- 
vent self-pollination,  as  maturing  the  pollen  either  before 
or  after  the  receptive  stage  of  the  stigma,  or  so  locating 
the  stamens  that  the  pollen  is  not  readily  deposited  on 
the  stigma  of  the  same  flower.*     In  some  cases,  pollen 
is  infertile  on  a  stigma  of  the  same  flower  or  plant  that 
is  abundantly  fertile  on  stigmas  of  other  plants  of  the 
same  species  (155). 

154.  Perfect,  Monoecious  (mo-no3'-cious)  and  Dioecious 
(di-re'-cious)  Flowers.     Flowers  containing  both  stamens 
and  pistils  (or  pistil),  as  in  the  apple,  tomato,  cabbage 
etc.,  are  called  perfect  or  hermaphrodite  (her-maph'-ro- 
dite);  those  containing  but  one  of  these  organs,  as  in  the 
melon,  Indian  corn  etc.,  are  called  imperfect  or  unisexual 
(u'-ni-sex'-u-al).t     Flowers  of  the  latter  class  are  called 
monoecious  when  the  stamen-bearing  (staminate  (stam'-i- 

*  Darwin's  work  "On  the  Various  Contrivances  by  which  Orchids  are 
Fertilized  by  Insects  "  describes  many  most  interesting  adaptations  of 
this,,  sort. 

t  The  terms  hermaphrodite,  unisexual  and  bisexual,  though  often  ap- 
plied to  flowers,  are  inaccurate. 


The   Fruit  and  the  Seed. 


101 


nate))  and  pistil-bearing  (pistillate  (pis'  -til  -late))  flowers 
are  both  produced  on  the  same  plant,  and  dioecious  when 
produced  on  different  plants*only,  as  in  the  hop  and  date. 
In  a  few  plants,  as  the  strawberry  (155)  and  asparagus, 
some  individuals  produce  perfect,  and  some  imperfect 
flowers. 

155.  Planting  with  Reference  to  Pollination  is  important 
in  certain  plants.  All  dioecious  plants  (154)  intended 
for  seed  or  fruit  must  have  staminate  and  pistillate  plants 
growing  near  together  or  they  will  not  be  productive. 
The  hop  plant  and  date  palm  are  of  this  class. 

The  flowers  of  many 
of  our  most  productive 
varieties  of  strawberry 
yield  little  or  no  pollen 
and  are  unproductive, 
unless  growing  near 
pollen-bearing  sorts 

FIG.  56.    Imperfect  flower  of  the  straw-      (FigS.  56,  57  ).    In  many 


FIG.  56. 


FIG.  57. 


varieties   of    American 

•  ,     .  . 

and    in     Certain 


FIG.  57.    Perfect  flower  of  same.    The 
numerous  pistils  appear   in   a  circular 
mass  at  the  center,  around  which   the      varieties    Of     the    pear 
stamens  are  seen  in  Fig.  57. 

the  pollen,  even  though 

produced  freely,  is  infertile  on  stigmas  of  the  same 
variety.  To  insure  fecundation,  it  is  wise  to  mingle  varie- 
ties in  fruit  plantations  rather  than  to  plant  large  blocks  of  a 
single  variety. 

SECTION  XL     THE  FRUIT  AND  THE  SEED 
156.  The  Fruit,  as  the  term  is  used  in  botany,  is  the 
mature  ovary  with  its  contents  and  adherent  parts,-  it 
may  be  hard  and  dry,  as  in  the  wheat  and  bean,  or  soft 


102  Principles  of  Plant  Culture. 

and  pulpy,  as  in  the  apple  and  melon.  But  in  common 
language  the  term  fruit  is  limited  to  the  pulpy  and  juicy 
part  of  certain  plants  that  normally  contains  or  supports 
the  seed  or  seeds.  To  avoid  explaining  botanical  terms, 
we  use  the  word  in  the  latter  sense.  In  this  sense,  the 
fruit  serves  the  plant  by  attracting  animals  that  can 
assist  in  disseminating  the  seed. 

The  seed,  as  we  have  seen,  is  the  fecundated  and  ma- 
ture ovule  (145),  and  its  normal  office  is  reproduction 
(16). 

157.  The  Fruit  Rarely  Develops  Without  Fecundation  of 
the  germ  cell  of  the  ovule  (150).    Varieties  of  the  apple 
and  pear  have   appeared,  however,  in  which  the  pulp 
develops  without   seeds.     The   fruit  of  the  banana  is 
almost    invariably    seedless.      The    cucumber,    grape, 
orange  and  fig  sometimes  develop  their  fruit  without 
fecundation  of  the  germ  cell.     These  instances  are  all 
exceptions  to  the  general  rule. 

158.  Seed  Production  Exhausts  the  Plant  far  more  than 
other  plant  processes.     The  seed  prepares  little  or  no 
food,  while  it  removes  from  other  parts  of  the  plant  a 
comparatively  large  amount  of  prepared  food,  which  it 
stores  up  in  a  concentrated  form  as  a  food  supply  for  the 
embryo  (55).     Many  plants  (all  annuals  and  biennials) 
are  killed  the  first  time  they  are  permitted  to  seed  freely, 
and  perennials  are  often  weakened  by  excessive  seeding.* 

159.  Prevention  of  Seeding  Prolongs  the  Life  of  Plants. 
Many  annual  flowering  plants,  as  sweet  peas,  dianthus 
etc.,  that  soon  perish  when  permitted  to  mature  their 

*  Double-flowered  varieties  of  the  annual  larkspur  (Delphinium),  that 
bear  no  seed,  have  become  perennial. 


The  Fruit  and  the  Seed.  103 

seed,  continue  to  bloom  throughout  the  summer  if  the 
flowers  are  persistently  picked.*  The  yield  of  cucum- 
bers, peas,  beans  and  other  garden  crops,  of  which  the 
product  is  gathered  immature,  may  be  considerably  in- 
creased by  preventing  the  ripening  of  seed. 

160.  Overbearing  Should  be  Prevented.     Certain  varie- 
ties of  some  of  our  cultivated  fruits,  as  the  apple,  plum 
and  peach,  tend  to  devote  an  undue  amount  of  their 
reserve  food  to  fruit  and  seed  production  in  favorable 
seasons,  which  if  permitted,  results  in  enfeeblement  or 
premature  death.     The  wise  cultivator  guards  against 
this  tendency  by  thinning  the  fruit  before  it  has  made 
much  growth,  thus  saving  the  tree  from  undue  exhaus- 
tion and  improving  the  quality  of  the  fruit  allowed  to 
mature. 

Thinning  should  be  done  as  early  as  the  fruits  can  be 
properly  assorted,  and  the  more  imperfect  ones  should 
always  be  removed.  The  proper  amount  of  thinning 
will  depend  upon  many  conditions,  as  age  and  vigor  of 
tree,  abundance  of  crop,  fertility  of  soil,  water  supply 
etc.  It  must  be  determined  by  judgment  and  experience. 

161.  The  Maturing  of  Seed  Injures  Fodder  Crops.     The 
food  value  of  straw,  from  which  the  ripe  grain  has  been 
threshed,  is  comparatively  small,  and  that  of  grass  and 
other  crops  intended  for  coarse  fodder  is  much  reduced 
by  permitting  the  seed  to  ripen  before  cutting. 

162.  The  Ripening  of  Fruits.     Green  fruits  assist  the 
leaves  in  food  preparation  to  "some  extent,  but  as  they 
begin  to  ripen,  the  process  is  reversed.     Carbonic  acid 
and  water  are  then  given  off,  while  oxygen  is  absorbed. 

*  See  foot  note  on  page  102. 


104  Principles  of  Plant  Culture. 

Fruits  first  become  sour  from  the  production  of  acids 
which  disappear  in  part  at  a  later  stage,  while  sugar  is 
notably  increased.  Kipening  is  favored  by  warmth,  and 
in  some  fruits  by  light. 

Some  fruits,  as  the  strawberry  and  peach,  increase 
rapidly  in  size  during  the  ripening  period,  provided  the 
water  supply  is  sufficient. 

Color  is  not  always  an  index  of  maturity.  Blackberries, 
currants,  and  certain  other  fruits  improve  in  edible 
quality  for  some  time  after  assuming  their  mature  color. 

Most  fruits  that  have  attained  nearly  normal  size,  ripen 
to  a  degree  when  detached  from  the  parent  plant.  Pears 
are  usually  improved  in  quality  if  picked  before  maturity 
and  ripened  in-doors.  The  grape,  however,  fails  to 
develop  its  sugar  if  prematurely  picked. 

After  a  certain  stage  of  maturity  is  reached,  all  vital 
processes  in  the  pulpy  part  of  the  fruit  cease,  and  disor- 
ganization (decay)  begins,  unless  prevented  by  a  preserv- 
ative process. 

SECTION  XII.  THE  GATHERING  AND  STORING  or  SEEDS 

163.  The  Stage  of  Maturity  at  which  Seeds  will  Germi- 
nate varies  greatly  in  different  plants  and  bears  no  direct 
relation  to  the  time  at  which  the  seeds  are  set  free  from 
the  parent  plant.  Seeds  of  the  tomato  will  germinate 
when  the  fruit  is  little  more  than  half  grown,  and  those 
of  the  pea  will  germinate  when  fit  for  table  use.  Seeds 
of  the  lemon  sometimes  germinate  within  the  fruit.  On 
the  other  hand,  seeds  of  the  thorn  *  and  juniper  rarely 
germinate  until  the  second  spring  after  their  production. 

*  Crataegus. 


The  Gathering  and  Storing  of  Seeds.  105 

Seeds  of  many  annual  and  biennial  plants,  as  the  cereals, 
cabbage  etc.,  may  germinate  as  soon  as  set  free  by  the 
parent  plant,  but  those  of  many  annual  weeds  and  of 
most  trees  and  shrubs  will  not  germinate  until  some 
months  afterward. 

Seeds  necessarily  gathered  immature  will  often  ripen 
sufficiently  for  germination  if  a  considerable  part  of  the 
plant  is  plucked  and  cured  with  them. 

Germinating  seeds  in  which  the  germination  process  is 
stopped  by  undue  drying  are  not  always  destroyed. 
Germination  may  be  resumed  on  access  to  water.  Seeds 
of  different  species  differ  widely  in  this  respect.  Those 
of  the  parsnip  and  carrot  cannot  endure  much  drying 
during  germination,  while  those  of  the  cereals  may  be 
repeatedly  dried  at  ordinary  temperatures  without  de- 
stroying their  vitality. 

164.  Immature   versus   Ripe    Seeds.     Seeds  not  fully 
grown  lack  a  part  of  their  normal  food  supply,  and  their 
embryo  is  probably  imperfectly  developed.     If  capable 
of  germination,  they  rarely,  if  ever,  produce  vigorous 
plants.     As  a  rule,  the  most  vigorous  plants  come  from 
fully-matured  seeds.     Immature  seeds,  persistently  used, 
may  tend  to  reduced  vigor,  early  maturity,  dwarfness 
and  shortened  life.     In  some  over- vigorous  plants,  as  the 
tomato,  slightly  immature  seed  may  tend  to  increased 
fruitfulness. 

Slightly  immature  seeds  usually  germinate  sooner  than 
fully  matured  ones. 

165.  The  Vitality  of  all  Seeds  is  Limited  by  Age,  but  the 
duration  of  the  vital  period  varies  greatly  in  different 
species.     Seeds  of  the  chervil  rarely  germinate  if  much 


106 


Principles  of  Plant  Culture. 


more  than  one  year  old,  while  those  of  the  gourd  family, 
the  tomato  and  celery  often  germinate  well  when  ten 
years  old. .  As  a  rule,  oily  seeds,  as  of  Indian  corn,  rape 
and  sunflower,  are  shorter  lived  than  starchy  seeds,  as 
wheat  and  rice.  The  following  table  gives  the  average 
period  during  which  the  seeds  named  are  reliable  for 
germination,  when  properly  cared  for:  * 


Duration  of 
Germinating  Power. 


Average.    Extreme. 
Years.     Years. 


Duration  of 
Germinating  Power. 
Av.    Ext'm. 
Yr».    Yrs. 


4  or 


Artichoke 

Asparagus 

Bean 

Bean — [Kidney.. 

Bean  — Soy 

Beet 

Borecole  or  Kale 

Broccoli 

€abbage 

Cardoon 

Carrot 

Cauliflower 

Celery 

Chervil 2  or 

Chervil  —  Sweet-scented. 

Chervil  —  Turnip-rooted 

Corn  Salad 

Cress  —  American 

Cress  —  Common  Garden 

Cress  —  Water 

Cucumber  —  Common 

Eggplant 

Endive 


6     10  Gumbo  or  Okra  .....................  5 

5  8  Hop  .........................................  2 

6  10  Kohl-Rabi  ..............................  5 

3       8  Leek  .......................................  3 

2  0  Lentils  ...................................  4 

G      10  Lettuce  ...................................  5 

5      10  Maize  or  Indian  Corn  ............  2 

5      10  Melon  —  Musk  ........................  5 

5      10  Melon  —  Water  .......................  G 

7  9  Mustard  —  Black  or  Brown..  4 
5      10  Onion  ......................................  2 

5      10  Parsnip  ...................................  2 

8  10  Parsley  ....................................  3 

3  6  Pea  .........................................  3 

1  Pumpkin  ...............................  6 

1  Rhubarb  .................................  3 

10  Salsafy  ....................................  2 

5  Sea-kale  ..................................  1 

9  Spinach—  Prickly-seeded  .....  5 

9  Squash  ....................................  6 

Strawberry  .............................  3 

Tomato  ...................................  4 

Turnip  ....................................  5 


1 

1 

5 

3 

5 

5 
10      10 

6      10 
10      10 


166.  Conditions  Affecting  the  Duration  of  Seed  Vitality. 

A  uniform  degree  of  humidity  and  temperature  tends  to 
prolong  the  vital  period  of  seeds,  by  causing  little  drain 
upon  the  life  of  the  living  cells.  Seeds  deeply  buried  in 
the  ground  are  often  capable  of  germination  at  a  great 
age,  and  kidney  beans  at  least  one  hundred  years  old, 
taken  from  an  herbarium,  are  said  to  have  germinated. 
In  these  cases,  the  seeds  were  subjected  to  few  variations 
in  humidity  and  temperature. 


From  "  The  Vegetable  Garden,"  Vilmorin,  Andrieux  &  Cie,  Paris. 


The  Gathering  and  Storing  of  Seeds.  107 

Seeds  usually  retain  vitality  longer  when  not  removed 
from  their  natural  covering,  probably  because  they  are 
thus  exposed  to  fewer  changes  of  humidity  and  temper- 
ature. Timothy  seeds,  that  become  hulled  in  threshing, 
lose  vitality  sooner  than  those  that  escape  hulling,  even 
when  the  two  sorts  have  been  kept  in  the  same  bag.  In- 
dian corn  is  said  to  retain  vitality  longer  on  the  cob  than 
shelled,  and  longer  when  the  ear  is  unhusked  than  if 
husked. 

167.  Moisture  is  an  Enemy  to  Stored  Seeds,  except  for 
the  class  that  requires  stratification  (170).  A  little 
moisture  in  stored  seeds  is  very  liable  to  cause  the  devel- 
opment of  fungi  (moulds)  that  may  destroy  the  embryo. 
Damp  seeds  are  also  liable  to  be  destroyed  by  freezing. 
It  is  important  that  seeds  be  dried  promptly  after  gathering, 
for  if  mould  once  starts,  subsequent  drying  may  not  de- 
stroy the  fungus;  the  latter  may  resume  growth  as  soon 
as  the  seed  is  planted,  thus  enfeebling  or  destroying  the 
embryo  before  it  has  time  to  germinate.  Drying  by 
moderate  artificial  heat  (not  higher  than  100°  F. )  is  wise 
with  seeds  gathered  in  cold  or  damp  weather. 

Oily  seeds,  as  of  Indian  corn,  sunflower,  and  the  cab- 
bage family  (cabbage,  cauliflower,  kohl-rabi,  Brussels 
sprouts,  ruta-baga,  rape,  turnip,  mustard)  cannot  safely 
be  stored  in  bulk  in  large  quantities,  except  in  cool 
weather. 

Seeds  are  shorter-lived  in  warm  than  in  cooler  climates. 

The  most  satisfactory  method  of  preserving  seeds  in 
quantity  is  to  inclose  them  in  bags  of  rather  loose  texture 
and  of  moderate  size,  and  to  store  these  in  a  cool,  dry  and 
airy  place. 


108  Principles  of  Plant  Culture. 

168.  Age  of  Seed  as  Affecting  the  resulting  Crop.  Seeds 
grown  the  same  or  the  preceding  season  produce,  as  a 
rule,  more  vigorous  plants  than  older  seeds.     They  may 
not,  however,  in  all  cases  produce  plants  that  are  most 
productive  of  fruit  or  seed,  for  excessive  vigor  is  gener- 
ally opposed   to   reproduction.     Cucumber   and    melon 
plants  grown  from  seed  three  or  four  years  old  are  often 
more  fruitful  than  those   from   fresh   seeds.     In   crops 
grown  for  parts  other  than  fruit  or  seed,  fresh  seeds  are 
undoubtedly  preferable,  but  in  crops  grown  for  seed  or 
fruit,  fresh  seed  may  not  always  give  as  large  returns  as 
seed  of  some  age.     This  subject  needs  further  investiga- 
tion. 

169.  How   Drying   Affects  the  Vitality  of  Seeds.     The 
vigor  of  seeds  is  probably  never  increased  by  drying 
them,  but  the  seeds  of  most  annual  and  biennial  plants 
may  become  air-dry  without  material  loss  of  vitality. 
The  seeds  of  many  shrubs  and  trees,  however,  lose  vital- 
ity rapidly  by  such  drying  and  those  of  some  species  are 
destroyed  by  it.     In  nature,  seeds  of  the  latter  class  are 
usually  dropped  from  the  parent  plant  before  becoming 
dry  and  are  soon  covered  by  leaves  or  other  litter  that 
keeps  them  moist.     Nurserymen  either  plant  such  seeds 
as  soon  as  they  are  ripe,  or  if  of  species  that  do  not  ger- 
minate as  soon  as  ripe,  they  imitate  nature  by  the  process 
known  as 

170.  Stratification  of  Seeds.     This  consists  in  mixing 
the  freshly-gathered  seeds  with  sand,  taking  care  that 
the  sand  is  kept  moist  until  the  time  for  sowing  arrives. 
Large  quantities  of  seeds  may  be  stratified  in  boxes,  by 
placing  the  moist  sand  and  seeds  in  alternate  layers,  or 


Decline  of  Growth  and  the  Rest  Period.          109 

the  layers  may  be  built  up  in  a  pile  on  the  ground.  The 
sand  should  be  coarse  enough  to  admit  some  passage  of  air 
between  the  particles  and  to  give  perfect  drainage.  The 
layers  should  not  much  exceed  an  inch  in  thickness,  ex- 
cept for  the  larger  seeds,  and  the  number  of  layers  should 
•not  be  so  large  as  to  prevent  proper  aeration  of  the  mass. 
Small  quantities  of  seeds  may  be  mixed  with  sand  or 
porous  loam  in  flower-pots.  Moisture  may  be  maintained 
in  the  boxes  or  pots  by  burying  them  a  foot  or  more  deep 
in  the  soil  in  a  well -drained  place,  or  by  storing  them  in 
a  moist  cellar.  Care  is  necessary  to  keep  mice  and  other 
vermin  from  stratified  seeds.  It  is  well  to  cover  pots  in 
which  valuable  seeds  are  stratified,  with  a  sheet  of  tin 
or  zinc;  metal  labels  are  best  for  distinguishing  different 
sorts  of  seed.  The  seeds  should  remain  stratified  until 
sowing  time,  when  they  may  be  sifted  out  of  the  sand  or 
sown  with  it,  as  is  more  convenient.  Seeds  that  do  not 
germinate  well  until  the  second  spring  after  maturity 
(163)  are  commonly  left  in  stratification  until  that  time. 

SECTION  XIII.     THE  DECLINE  OF  GROWTH  AND  THE 
BEST  PERIOD 

171.  Annual  plants  usually  perish  soon  after  maturing 
their  seed.  In  other  plants,  a  certain  period  of  vital 
activity  is  followed  by  one  in  which  growth  gradually 
declines  until  it  almost  or  entirely  ceases.  In  woody 
plants,  the  cells  become  thickened  and  a  part  of  the  rudi- 
mentary leaves  change  to  bud-scales,  which  inclose  the 
growing  point  (128).  In  deciduous  (de-cid'-u-ous)*  trees 
and  shrubs,  the  chlorophyll  and  starch,  with  most  of  the 

*  Deciduous  trees  and  shrubs  are  those  of  which  the  leaves  perish  at 
the  beginning  of  the  rest  period. 


110  Principles  of  Plant  Culture. 

potash  and  phosphoric  acid  contained  in  the  leaves,  are 
withdrawn  into  the  woody  parts  (127),  while  the  leaves 
themselves  are  detached  and  fall.  The  root-hairs  also 
die  in  many,  if  not  all  plants.  The  leaves  of  many  trees 
and  shrubs  assume  striking  colors  as  they  approach  ma- 
turity. In  perennial  herbs,  the  nutritive  matters  in  the 
foliage  and  stem  are  withdrawn  to  the  underground 
parts.  A  period  of  almost  complete  repose  ensues, 
during  which  the  plant  owing  to  the  dormant  condition 
of  its  protoplasm  is  able  to  endure,  without  harm,  ex- 
tremes of  temperature  or  dryness  that  would  be  fatal  in 
its  active  state. 

Growth  ceases  in  many  trees  and  shrubs  earlier  than  is 
often  supposed.  Most  orchard  and  forest  trees  of  mature 
age  grow  little,  if  any,  after  midsummer  in  the  temper- 
ate zones.  Cultivation,  mulching  and  manuring  tend  to 
prolong  the  growth  period  (200). 

172.  The  Rest  Period  is  Not  Peculiar  to  the  Temperate 
Zones,  but  occurs  in  the  tropics  as  well.  It  can  be  as- 
cribed in  part  to  the  change  of  seasons,  as  a  few  familiar 
examples  will  indicate.  Tubers  of  the  earlier  varieties 
of  the  potato,  that  ripen  in  northern  countries  by  the  be- 
ginning of  August,  do  not  sprout  if  left  in  the  ground 
till  October,  but  if  stored  in  a  cellar  during  winter  at  a 
temperature  little  above  freezing,  they  often  begin  to 
sprout  in  March.  Bulbs  of  the  crocus,  tulip,  narcissus, 
crown  imperial  etc.,  that  form  in  spring,  lie  dormant  in 
the  warm  soil  during  summer  and  early  autumn,  but  start 
vigorously  in  the  colder  soil  of  the  late  autumn  or  the 
succeeding  spring.  The  buds  of  many  trees,  that  form 
in  summer  for  the  next  year's  foliage  and  flowers,  remain 
dormant  during  the  hot  weather  of  August  and  Septeni- 


Decline  of  Growth  and  the  Eest  Period.          Ill 

ber,  to  push  vigorously  in  the  first  warm  days  of  spring. 
The  rest  period  is  to  be  regarded  as  a  normal,  if  not  a 
necessary  factor  of  plant  life. 

173.  Most  Plants  Under  Glass  Require  Rest  from  time  to 
time,  or  they  do  not  thrive.     The  rest  is  provided  either 
by  keeping  them  at  a  lower  temperature  than  is  favorable 
to  growth,  or  by  submitting  them  to  a  degree  of  dry  ness 
that  prevents  growth.    The  latter  is  preferable  for  plants 
native  in  the  tropics,  where  they  naturally  lie  dormant 
during  the  dry  season. 

174.  The  Time  of  Leaf  Fall  is  an  Index  of  Wood  Maturity 
in  healthy  deciduous  trees  and  shrubs.     In   these,  the 
coloring  and  fall  of  the  leaves  in  autumn  is  not  necessarily 
clue  to  frost,  but  results  from  the  dormant  condition  that 
accompanies    maturity.     As   a  rule,  the   more   mature 
leaves  are  precipitated  by  the  first  autumn  frosts.    Those 
less  mature  usually  remain  until  the  more  severe  frosts. 
In  trees  with  well -ripened  wood,  the  leaves  at  the  tip  of 
the  shoots  usually  fall  before,  or  not  later  than,  those  on 
the  older  parts  of  the  tree.     With  poorly-  matured  wood 
the  reverse  is  the  case.     In  a  few  deciduous  trees,  as  the 
beech  and  some  oaks,  many  of  the  mature  leaves  remain 
on  through  the  winter. 

175.  Hardiness  Depends  upon  the  Degree  to  which  tlie 
Dormant  State  is  Assumed.     Since  the  most  severe  cli- 
matic extremes  coine  during  the  natural  rest  period  of 
plants,  the  ability  of  the  plant  to  endure  these  extremes 
depends  upon  the  extent  to  which  the  protoplasm  be- 
comes dormant  during  the  decline  of  growth.    As  a  rule, 
a  given  plant  is  hardy  (10)  in  a  locality  in  which  the 
duration  and  the  warmth  of  the  growing  season  are  suf- 


112  Principles  of  Plant  Culture. 

ficient  to  complete  and  fully  mature  its  normal  amount 
of  growth.  Varieties  of  the  apple  and  other  trees,  that 
so  far  complete  their  growth  in  any  given  locality  that 
their  leaves  fall  before  hard  frosts,  are  rarely  injured  in 
winter,  while  those  that  continue  growth  until  their 
foliage  is  destroyed  by  freezing  suifer  in  severe  winters. 
Deciduous  trees  are  liable  to  destruction  in  severe  win- 
ters in  a  climate  where  none  of  the  leaves  fall  before 
hard  frosts,  as  is  the  case  with  the  peach,  apricot  and 
nectarine  in  northern  United  States. 

176.  Individual    Plants  Cannot  Adjust  Themselves  to  a 
New  Environment,  except  to  a  slight  extent.     The  power 
to  complete  the  annual  growth  processes  and  become 
sufficiently  dormant  to  endure  the  rigor  of  the  rest  period 
in  any  given  locality  is  inherited,  and  not  acquired.    We 
are,  therefore,  able  to  do  very  little  toward  inuring  or 
acclimatizing  (ac-cli'-nia-tiz-ing)  individual  plants  to  an 
environment  to  which  they  were  not  adapted  by  nature. 
We  may,  however,  through  the  variations  of  offspring 
(18),  secure  varieties  in  some  cases  that  can  endure  an 
environment  which  the  parents  could  not  endure. 

177.  Plant  Processes  during  the  Rest  Period  may  not 
entirely  cease.     Although  food   preparation   is  wholly 
suspended,  root  growth  and  the  callusing  (73)  of  injured 
root  surfaces  proceed  to  some  extent  during  the  winter  in 
unfrozen  layers  of  soil;  and  in  sufficiently  mild  weather, 
the  reserve  food  in  the  stem  gradually  moves  in  the  direc- 
tion of  the  terminal  buds. 

178.  Cuttings  (358)  of  Woody  Plants  are  Preferably  Made 
in  Autumn  in  climates  of  severe  winters  and  buried  in  the 
ground  below  the  limit  of  hard  freezing,  in  order  that 


Decline  of  Growth  and  the  Rest  Period.          113 

callusing  (73)  and  the  transfer  of  food  may  make  some 
progress  before  the  final  planting. 

179.  The  "  Turn  of  the  Year."     Toward  the  close  of  the 
dormant  season,  vegetation,  as  if  benefited  by  the  rest,  is 
prepared,  to  start  with  renewed  vigor,  even  at  moderate 
temperatures.     Buds,  that  remained  dormant  during  the 
latter  part  of  the  previous  summer,  push  into  growth 
with  the  first  warm  days  of  spring,  and  many  seeds,  that 
could  not  be  induced  to  germinate  the  preceding  autumn, 
start  with  vigor  as  soon  as  the  soil  is  sufficiently  warm. 

The  cause  for  this  energetic  resumption  of  plant  growth 
after  the  rest  period  is  not  well  understood,  but  exposure 
to  cold,  in  the  case  of  temperate  plants,  and  to  prolonged 
dryness  in  that  of  tropical  ones,  doubtless  explains  it  in 
part,  for  it  is  well  known  that  potato  tubers  may  be  in- 
duced to  start  their  buds  soon  after  maturity  by  exposing 
them  to  the  sun  a  few  days,  or  by  placing  them  for  a  like 
time  in  a  refrigerator  containing  ice.  By  these  means, 
farmers  of  Tennessee  grow  a  second  crop  of  potatoes  in 
the  latter  part  of  summer  and  during  autumn. 

Plants  under  glass  usually  thrive  better  after  mid- 
winter than  before,  and  the  most  favorable  time  to  plant 
seeds  of  greenhouse  plants  is  toward  the  close  of  the 
natural  rest  period. 

180.  The  Round  of  Plant  Life  has  now  been  traced,  from 
the  first  swelling  of  the  planted  seed,  through  the  de- 
velopment of  the  embryo  into  the  plantlet,  the  penetra- 
tion of  the  root  into  the  dark  and  damp  soil  cavities,  the 
absorption  and  conduction  of  water  with  its  food  mate- 
rials in  solution,  co-operating  with  the  sunlight  and  car- 
bonic acid  in  the  mysterious  laboratory  of  the  leaf,  in 


114  Principles  of  Plant  Culture. 

building  up  the  plant  body  into  node  and  internode,  leaf, 
bud,  branch,  flower,  fruit  and  seed;  through  growth  de- 
cline, leaf  fall  and  winter  sleep,  to  the  renewed  vigor  of 
another  springtime. 

In  our  study  of  the  round  of  plant  life,  we  have 
assumed  the  environment  to  be  favorable.  But  in  the 
practical  culture  of  plants,  we  are  constantly  meeting 
with  adverse  conditions  of  environment.  Talent  for 
plant  culture  lies  in  the  ability  to  discern  these  adverse 
conditions  by  the  appearance  of  the  plant,  and  in  know- 
ing how  to  correct  them.  We  will,  therefore,  next  con- 
sider the  plant  as  affected  by  unfavorable  conditions  of 
environment. 


The  following  books  are  recommended  for  reading  in 
connection  with  the  preceding  chapter:  How  plants 
Grow,  Gray;  Lessons  in  Botany,  Gray;  Botanical  Text- 
Book,  Gray;  A  Treatise  on  the  Physiology  of  Plants, 
Sorauer;  The  Soil,  King;  The  Fertility  of  the  Land, 
Roberts. 


CHAPTER  III 

THE    PLANT   AS    AFFECTED    BY    UNFAVORABLE 
ENVIRONMENT 

181.  Factors  of  Environment.     The  plant  environment 
is  mostly  comprehended   under  the  terms,  climate,  soil, 
animals  and  other  plants.     But  as  these  are  more  or  less 
complex  influences,  it  is  well  to  analyze  them  and  to  con- 
sider separately  the  component  factors  of  each. 

SECTION  I.     THE  PLANT  AS  AFFECTED  BY  UNFAVOR- 
ABLE TEMPERATURE 

A  — THE  PLANT  AS  AFFECTED  BY  EXCESSIVE  HEAT 

182.  Transpiration  Increases  with  the  Degree  of  Heat. 

The  most  common  effect  of  heat  upon  plants  is  the  droop- 
ing of  the  foliage,  due  to  excessive  transpiration  (75). 
With  insufficient  water,  this  may  occur  at  a  temperature 
that  is  normal  for  the  plant.  But  with  a  water  supply  that 
is  sufficient  at  ordinary  temperatures,  transpiration  may  be 
so  much  increased  by  an  overheated  atmosphere  that  the 
roots  are  unable  to  supply  the  plant  with  sufficient  water, 
and  as  the  result,  the  cells  become  partially  emptied  and 
the  foliage  droops.  Herbaceous  plants  in  an  overheated 
greenhouse  or  hotbed  are  sometimes  so  prostrated  from 
excessive  loss  of  water  as  to  appear  dead,  but  unless  the 
heat  has  been  sufficient  to  destroy  their  protoplasm,  or 
the  heated  period  has  been  protracted,  they  will  recover 
when  normal  temperature  and  water  supply  are  restored. 

(115) 


116  Principles  of  Plant  Culture. 

183.  Evergreen  Trees  are  sometimes  Destroyed  by  In- 
timely  Warm  Weather  in  spring.     With  a  soil  so  cool  that 
the  roots  are  inactive,  a  sudden  rise  of  atmospheric  tem- 
perature, espcially  if  accompanied  by  a  drying  wind, 
may  so  far  reduce  the  water  in  the  leaves  of  evergreen 
trees  as  to  cause  death  of  the  foliage  and  even  of  the 
trees  themselves.     This  most  frequently  happens  in  the 
seed-bed,  in  compact  nursery  plantations,  or  with  recently - 
transplanted  evergreen  trees.     It  is  most  disastrous  on 
poorly- drained  clay  soils  that  have  a  sunny  exposure, 
and  at  times  when  the  ground  is  deeply  frozen. 

The  preventives  to  be  observed  are,  a,  means  that  will 
prevent  the  tardy  thawing  of  the  ground,  as  thorough 
drainage  and  not  too  close  planting;  5,  means  that  will 
prevent,  in  a  measure,  exposure  to  the  sun,  as  planting 
on  a  northern  slope  or  shading  the  trees  (414);  c,  means 
that  tend  to  prevent  the  deep  freezing  of  the  soil,  as  pro- 
viding wind  breaks  which  tend  to  retain  the  snow  (204). 

184.  A  Temperature  of  122°  F.  is  Fatal  to  the  Protoplasm 
of  most  land    plants.     Aquatic   plants  and  the   more 
watery  parts  of  land  plants  perish  at  a  somewhat  lower 
temperature.     Watery  fruits,  as  tomatoes  and  gooseber- 
ries, and  the  younger  leaves  of  deciduous  trees,  are  some- 
times destroyed  by  full  exposure  to  the  sun's  rays  in 
very  warm  weather.     An  occasional  sprinkling  of  the 
plants  and  of  the  soil  about  them  will  usually  prevent 
this  result. 

185.  Plants    Under   Glass   should   Not  be  Sprinkled  in 
Bright   Sunshine.     Drops  of  water   upon   the   leaves  of 
plants  often  act  as  lenses  in  converging  the  rays  of  the 
sun,  and  in  a  closed  greenhouse  or  hotbed  may  cause  a 


Plants  as  Affected  by  Heat. 


117 


heat  that  is  fatal  to  the  foliage  beneath  them.     This  may 
explain  the  brown  spots  so  often  observed  upon  the  leaves 

of  indoor  plants  that  have  been 
sprinkled  in  bright  sunlight. 
Sometimes,  but  rarely,  this 
trouble  occurs  in  the  open  air. 
186.  Sun-scald  is  the  term  ap- 
plied to  an  affection  of  the 
trunk  and  larger  branches  of 
certain  not  quite  hardy  trees, 
usually  upon  the  south  or  south- 
west side,  in  which  the  bark 
and  cambium  layer  (69)  are 
more  or  less  injured  (Fig.  58). 
In  severe  cases,  the  cambium 
is  totally  destroyed,  and  the 
loosened  bark  splits  longitudin- 
ally or  becomes  detached.  The 
eifect  is  apparently  the  same  as 
when  a  tree  is  exposed  to  the 
heat  of  a  fire.  Sun-scald  is 
most  common  in  young  trees 
and  appears  to  be  due,  in  some 
cases,  to  the  superheating  of  the 
cambium  in  summer — in  others 
to  a  return  of  severe  freezing 
weather  after  a  period  suf- 
ficiently warm  to  excite  the 

FIG.  58.    Showing  effects  of  sun-   p^hinni  pplU  to  flrtivitv        A 
scald  on  trunk  and  branches  of  C  tlVlty.      ^ 

silver  maple  tree,  Acer  dasycar-   preventive     is     to    shade     the 

trunk  and  larger  branches  by 

inclosing  them  with  straw  or  similar  material,  or  with  a- 
lath  screen  (Fig.  59). 


118 


Principles  of  Plant  Culture. 


187.  Potato  Foliage  is  often  Injured  by  Sun  Heat  in  sum- 
mer, as  is  shown  by  the  browning  of  the  leaves  from  the 
tip  and  edges  toward  the  center,  or 
on  the    border   of  holes    made  by 
insects.     This    affection,   known    as 
tip-burn,  is  due  to  the  destruction  of 
protoplasm  in  the  cells  and  is  often 
mistaken  for  the  work  of  fungus.    It 
is  most  serious  in  dry  seasons.     ]^o 
remedy  for  it  is  known,  but  it  may  be 
in  part  avoided  by  selecting  varieties 
least  subject  to  it. 

B  — THE  PLANT  AS  AFFECTED  BY  EX- 
CESSIVE COLD 

188.  The  Immediate  Effect  of  Cooling 

the  Plant  is  to  check  the  activity  of 
its  vital  processes.     When  a  certain 
degree  of  cold  is  reached,  the  proto- 
plasm loses  its  power  to  imbibe  water 
(63);  hence  the  plant  tissues  become 
less  turgid,  and  the  foliage    droops 
somewhat.     With  a  sufficient  reduc- 
tion of  temperature,  ice  crystals  form 
within  the  tissues  and  the  succulent 
parts  of  the  plant   assume  a  glassy 

FIG.  59.    Trunk  of  ap-   A  _  _.  _ 

pie  tree  inclosed  in  lath  appearance.     The   foliage   of  many 
screen,  plants,  as  celery,  parsnip  etc. ,  assumes 

an  abnormal  position  when  frozen. 

189.  The  More  Water  Plant  Tissues  Contain,  the  Sooner 
they  Freeze.  Since  the  water  of  plants  is  not  pure,  but 
is  a  solution  of  various  substances,  it  does  not  freeze  at 
the  freezing  point  of  pure  water  (32°  F. ),  but  at  a  lower 


Plants  as  Affected  by  Cold.  119 

temperature,  determined  by  the  degree  of  concentration 
of  the  solution,  or  the  intimacy  with  which  it  is  com- 
bined with  the  tissues  of  the  plant.  The  more  thoroughly 
dormant  the  condition  of  a  plant,  or  part  of  a  plant,  the 
less  water  does  it  contain,  and  the  better  is  it  able  to  endure 
cold  (175). 

190.  The  Power  of  Plants  to  Endure  Cold  depends  upon 
various  conditions,  aside  from  the  amount  of  water  con- 
tained, as 

a — 'Hcml'ity.  Plants  by  nature  possess  widely  differ- 
ing powers  to  endure  cold.  The  Anwctochilus  (a-no3c'- 
to-chi'-lus)  perishes  when  exposed  for  a  considerable 
time  to  a  temperature  of  42°  F.,  while  other  plants,  as 
the  common  chick  weed,*  are  uninjured  by  prolonged 
cold,  far  below  the  freezing  point  (176). 

b  —  The  rate  of  thawing  of  the  frozen  tissues.  The 
more  slowly  the  thawing  takes  place,  the  less  likely  is 
the  frozen  part  to  suffer  injury.  Many  bulbs,  tubers  and 
roots  which  survive  the  severest  winters  within  the  soil, 
where  they  thaw  slowly,  are  destroyed  by  moderate 
freezing  if  quickly  thawed.  Frost-bitten  plants  are  sel- 
dom injured  when  sheltered  from  the  morning  sun  by  a 
dense  fog,  which  causes  them  to  thaw  slowly.  Apples, 
covered  in  the  orchard  in  autumn  by  leaves,  sometimes 
pass  a  severe  winter  with  little  harm. 

When  the  water  that  is  withdrawn  from  the  tissues  in 
the  freezing  process  is  gradually  set  free  by  slow  thaw- 
ing, it  may  be  absorbed  by  them  again  and  little  or  no 
harm  results. 

c  —  The  length  of  time  the  tissues  remain  frozen.  A  com- 
paratively slight  degree  of  frost,  if  prolonged,  may  act 

*  Stellaria  media. 


120  Principles  of  Plant  Culture. 

more  injuriously  than  a  severer  degree  of  shorter  dura- 
tion. Prolonged  freezing  is  especially  injurious  when 
the  frozen  parts  are  subjected  to  drying  wind,  which 
evaporates  their  water,  while  the  frozen  condition  pre- 
vents movement  of  their  fluids. 

d  — The  frequency  with  which  freezing  and  thawing  are 
repeated.  Frequent  slight  freezing  and  thawing  are  far 
more  injurious  than  a  prolonged  frozen  condition,  even 
though  the  latter  occurs  at  a  much  lower  temperature. 
Winter  wheat  and  rye,  and  strawberry  beds  are  often 
more  damaged  in  mild  winters,  in  which  freezing  and 
thawing  weather  alternate,  than  in  more  severe  ones, 
when  the  temperature  is  mostly  below  freezing.  The 
chief  damage  is  usually  done  to  these  crops  in  late  au- 
tumn and  early  spring. 

e — The  previous  treatment  of  the  plant.  Plants  grown 
by  artificial  heat  may  be  far  less  able  to  endure  cold  than 
others  of  the  same  varieties  grown  in  the  open  air,  pos- 
sibly owing  to  the  more  succulent  condition  of  the  former. 
Gardeners  harden  plants  grown  under  glass,  by  gradually 
exposing  them  to  the  cooler  out- door  atmosphere,  before 
removing  them  to  the  open  ground. 

f — The  treatment  of  the  frozen  tissues.  Handling  plants, 
fruits  or  vegetables  while  frozen  greatly  aggravates  the 
damage  from  frost,  probably  because  the  handling  in- 
creases laceration  of  the  cells  by  the  ice  crystals  within 
them. 

191.  Frost-Injured  Plants,  Fruits  or  Roots  May  often  Be 
Saved  from  serious  damage,  if  promptly  placed  under 
conditions  that  cause  the  slowest  possible  thawing  of  the 
tissues,  as  shading  from  the  sun's  rays,  immersing  in  ice 


Plants  as  Affected  by  Cold.  121 

water  or  covering  with  snow.  They  should  be  handled  as  little 
and  as  carefully  as  possible  while  frozen.  Sprinkling  with 
cold  water  is  often  sufficient  to  restore  frost-bitten  plants. 
Aside  from  the  death  of  tender  plants  by  cold,  more 
or  less  hardy  species  suffer  injury  in  a  variety  of  ways, 
of  which  the  following  are  examples: 

192.  Destruction  of  Terminal  Buds  by  Cold.     In  plants 
which  do  not  mature  their  terminal  buds,  in  autumn,  as 
the  raspberry,  sumac,  grape  etc.,  destruction  of  the  tips 
of  growing  shoots  by  frost  is  a  regular  occurrence  in 
climates   of  severe   winters.     The   distance  which   the 
shoots  are  killed  back  depends  upon  the  succulency  of 
the  growth,  the  severity  of  the  winter  and  the  natural 
power  of  the  plant  to  endure  cold.     Plants  thus  affected 
are  not  always  to  be  regarded  as  tender,  since  they  often 
grow  wild  in  climates  of  very  severe  winters. 

193.  The  Darkening  of  the  Wood  (black-heart)  of  certain 
trees,  as  the  pear,  in  climates  of  severe  winters,  appears 
to  be  a  chemical  effect  of  the  cold.     It  begins  at  the  cen- 
ter of  the  stem  and  in  extreme  cases  may  extend  clear  to 
the  cambium,  when  the  bark  ceases  to  adhere,  and  the 
tree  or  branch  thus  affected  dies.     In  stone  fruits,  this 
trouble  is  often  accompanied  by  a  flow  of  gum.     If  the 
coloring  of  the  wood  does  not  extend  to  the  cambium, 
the  tree  or  branch  may  survive,  but  the  first  season7  s 
growth  thereafter  is  generally  feeble  and  the  fruit  or  the 
seed  crop  often  fails.     Daring  the  second  season,  healthy 
growth  may  be  resumed,  but  the  heart- wood  is  rarely  or 
never  restored  to  its  normal  color.     Black-heart  often 
results  from  other  causes  than  cold,  as  from  bacteria  that 
gain  access  to  the  heart- wood  through  wounds  (418). 

8 


122  Principles  of  Plant  Culture. 

Other  chemical  changes  result  from  cold,  as  the  sweet- 
ening of  potato  tubers  when  chilled,  the  removal  of  as- 
tringency  from  the  wild  grape  and  persimmon,  and  the 
heightening  of  the  flavor  of  the  parsnip. 

194.  Tree  Trunks  are  sometimes  Split  Open  by  Severe 
Freezing,  the  split  remaining  open  until  the  return  of 
mild  weather.     This  most  often  occurs  in  hard-wooded, 
deep-rooted,  deciduous  trees,  as  the  oak,  and  appears  to 
result  from  the   more   rapid   contraction   of  the   outer 
layers  of  the  wood  in  a  sudden  fall  of  temperature.     The 
rents  are  usually  overgrown  by  the  next  annual  wood 
layer  (71). 

The  splitting  down  of  the  main  branches  of  certain 
varieties  of  the  apple  tree  appears  to  be  favored  by  the 
expansive  force  of  ice  in  narrow  crotches,  which  retain 
snow  and  water.  Varieties  the  branches  of  which  leave 
the  trunk  at  a  wide  angle  are  not  subject  to  this  trouble. 

195.  Bark-Bursting  on  the  trunks  of  young  apple  trees 
often  occurs  when  freezing  weather  overtakes  late-grow- 
ing and  hence  poorly-matured  wood.     In  severe  cases, 
the  bark  splits  longitudinally  clear  through  the  cambium 
layer  and  from  the  ground  to  the  lower  branches;  and 
the  bark   is  loosened  from   the   wood   nearly  or  quite 
around  the  trunk.     Such  trees  are  practically  ruined, 
but  trees  slightly  injured  by  bark-bursting  may  fully 
recover. 

Bark-bursting  is  usually  most  severe  on  deep,  rich, 
moist  soil  and  in  seasons  that  favor  late  growth,  or  in 
which  freezing  weather  occurs  unusually  early.  Late- 
growing  varieties  are  most  subject  to  it.  Its  occurrence 
is  lessened  by  treatment  that  favors  early  maturity  of  the 
wood  (200,  201). 


Plants  as  Affected  by  Cold.  123 

196.  Root-Killing   of  trees.     When  a  very  dry  autumn 
passes  to  winter  without  rain  or  snow,  the  surface  layers 
of  the  soil  sometimes  freeze  so  severely  as  to  destroy  the 
roots  of  young  trees.    Boot- killing  is  usually  most  serious 
on  light  soils,  and  on   one-year-old,  root-grafted   (391) 
nursery  trees,  especially  when  grafted  with  short  cions 
(386).     With  very  severe  freezing  on  bare  ground,  root- 
killing    sometimes  occurs  on  soil   well   supplied  with 
water.     The  destruction  of  the  roots  may  be  complete  or 
only  partial.     In  the  latter  case,  the  tree,  if  of  a  vigor- 
ous  variety,  may  largely  outgrow  the  trouble,  though 
complete  recovery  is  rare. 

Treatment  that  prevents  late  growth  (200,  201),  or 
mulching  the  ground  about  trees  tends  to  avert  root- 
killing. 

197.  Flower-Buds  are  often   Destroyed  by  Cold   while 
other  parts  of  the  plant  are  uninjured.     This  frequently 
occurs  in  the  peach,  apricot,  nectarine  and  certain  species 
of  the  plum  in  climates  of  rather  severe  winters,  espe- 
cially after  the  buds  have  been  somewhat  excited  by 
unseasonable  warm  weather.   Flower-buds  thus  destroyed 
are  dark -colored  at  the  center. 

198.  Flowers  are  Especially  Sensitive   to   Cold.     Fruit 
crops  are  usually  wholly  or  in  part  cut  off  if  a  slight 
frost  occurs  during  bloom,  and  in  certain  fruits,  as  the 
apricot  and  some  species  of  the  plum,  the  blossoms  some- 
times appear  to  be  destroyed  by  a  degree  of  cold  that 
does  not  descend  to  the  freezing  point,  possibly  through 
interference  with  pollination  or  pollen  germination  (151). 
When  the  freezing  is  accompanied  with  snow,  however, 
open  flowers  may  escape  without  harm,  probably  owing 
to  the  slow  extraction  of  the  frost  (190  b). 


124  Principles  of  Plant  Culture. 

199.  Low  Plants  are  often  Destroyed  by  Ice,  especially 
when  the  ice  layer  forms  in  direct  contact  with  the  soil 
about  them  and  remains  for  a  time  after  the  return  of 
warm  weather.     The  same  result  is  sometimes  produced 
by  a  covering  of  snow,  of  which  the  top  has  formed  into 
a  crust  of  ice.     Winter  grain  and  strawberry  plants  are 
often  smothered  in  this  way.     Surface  drainage  of  ground 
devoted  to  such  crops  is  highly  important. 

SECTION  II.     METHODS  OF  AVERTING  INJURY  BY  COLI> 

A  — DURING  THE  DORMANT  PERIOD 

a  —  By  Treatment  of  the  Soil. 

200.  A  Dry  Soil  Favors  Wood  Maturity,  while  an  abun- 
dant water  supply  retards  it.    Soil  treatment  that  restricts 
the  water  supply  toward  the  close  of  the  growing  period 
tends,  therefore,  to  hasten  wood  maturity  and  thus  to 
reduce  damage  from  cold  (175).     Tillage  should  be  early 
discontinued  about  trees  liable  to  winter  injury,  and  in 
wet  seasons,  mulching  should  be  removed.     Oats,  buck- 
wheat or  clover  sown  in  the  nursery  or  orchard  in  late 
summer  promotes  wood  maturity  by  increasing  evapora- 
tion from  the  soil  and  is  further  useful  as  a  covering  to 
the  ground  in  winter  (196).     Draining  heavy  or  wet 
soils  promotes  wood  maturity  by  promptly  removing  sur- 
plus water. 

b  —  By  Treatment  of  the  Plant. 

201.  Pinching  the  Terminal  Buds  (416  a)  a  few  weeks 
before  the  time  for  leaf  fall  favors  wood  maturity  by 
checking  growth,  as  does  the  removal  of  the  younger 
leaves,  in  which  food  preparation  is  most  active.     These 


During  the  Dormant  Period.  125 

methods  may  be  employed  upon  young  trees — especially 
nursery  trees,  which  are  very  liable  to  make  late  growth. 
Early  gathering  of  the  fruit  from  trees  of  late  varieties 
also  tends  to  hasten  wood  maturity. 

202.  Protection  with  Non-Conducting  Materials  prevents 
damage  from  cold  in  many  herbaceous  and  shrubby 
plants  in  climates  where  they  are  not  fully  hardy.  By 
covering  such  plants  with  straw  or  other  litter,  or  with 
soil,  we  lessen  to  some  extent  the  intensity  of  the  cold, 
but  —  more  important  —  we  prevent  frequent  freezing 
and  thawing  (190  d),  and  in  a  measure,  the  heaving  of 
the  ground,  which  on  heavy  or  wet  soil  is  destructive  to 
the  roots  of  plants.  A  covering  of  straw,  leaves  or  other 
litter  is  preferable  for  low,  herbaceous  plants,  as  straw- 
berries. The  covering  should  not  exceed  an  inch  or  two 
in  thickness,  otherwise  the  plants  may  be  smothered  in 
warm  winter  weather.  For  taller  plants,  as  the  grape 
and  raspberry,  the  soil  is  usually  the  most  convenient 
and  satisfactory  covering,  as  a  litter  covering  tends  to 
attract  mice,  that  often  injure  woody  stems.  To  assist 
in  bending  down  the  stems,  a  little  earth  is  usually  re- 
moved at  the  base  on  the  side  toward  which  they  are  to 
be  bent.  Shrubs  too  large  for  bending  down  may  be  in- 
closed in  straw  or  similar  material. 

303.  A  Northerly  Exposure  is  generally  Least  Trying  to 
Plants  in  winter,  because  it  is  least  subject  to  fluctuations 
in  temperature.  The  influence  of  the  sun  is  here  less 
perceptible  and  snow  remains  longer  than  upon  other 
exposures.  The  summit  of  a  hill  is  usually  less  trying 
than  a  valley,  because  the  cold  air  tends  to  seek  the  lower 
places,  especially  in  still  weather  (210). 


126  Principles  of  Plant  Culture. 

204.  Wind-Breaks,  i.  e.,  plantings  of  trees  intended  to 
break  the  force  of  prevailing  winds,  act  beneficially  in 
lessening  damage  from  cold,  in  so  far  as  they  prevent 
snow  from  drifting  off  the  soil  and  mitigate  the  effects 
of  drying  winds  (190  c). 

B  —  METHODS  OF  AVERTING  INJURY  FROM  COLD  DURING 
THE  GROWING  PERIOD 

205.  Plants  are  much  more  susceptible  to  injury  from 
cold  during  their  growth  period  than  during  their  dor- 
mant period  (171).     Comparatively  few  plants,  however, 
are  injured  by  cold  at  any  season  until  the  temperature 
falls  below  the  freezing  point  of  water  (32°  F.,  O°C.), 
or  when  so-called  hoarfrost  occurs.     It  is  this  extreme 
that  we  have  chiefly  to  fear  and  to  guard  against  during 
the  growing  period. 

206.  The  Cause  of  Hoarfrost.    A  sponge  saturated  with 
water  cannot  be  compressed  in  the  least  unless  a  portion 
of  the  water  escapes.     If  it  is  but  half  saturated,  it  may 
be  compressed  somewhat  without  any  escape  of  the  liquid, 
but  if  the  compression  passes  a  certain  limit,  the  water 
will  begin  to  escape. 

The  air  is  like  a  sponge  in  being  capable  of  taking  up 
a  certain  amount  of  water.  But  the  amount  of  water  the 
air  can  take  up  depends  very  much  upon  its  temperature, 
its  capacity  for  water  increasing  as  the  temperature  rises, 
and  decreasing  as  it  falls. 

Suppose  a  given  amount  of  air  at  a  temperature  of  50° 
F.  has  taken  up  all  the  water  it  can  hold  at  that  tem- 
perature. It  is  clear  from  what  has  just  been  said,  that 
if  the  temperature  of  this  air  is  reduced,  some  of  its  water 


Injury  from  Cold  During  Growing  Period.        127 

will  be  set  free  or  precipitated.  If  the  air  were  only  half 
saturated  at  50°  F.,  its  temperature  could  be  reduced 
considerably  before  any  of  its  water  would  be  precipitated; 
but  when  a  certain  degree  of  cooling  is  reached,  the  air 
will  no  longer  be  able  to  hold  all  of  its  water,  and  a  part 
will  be  precipitated.  The  cooling  of  the  air  corresponds 
to  the  compression  of  the  sponge.  The  atmosphere 
always  contains  more  or  less  water  in  the  form  of  watery 
vapor,  and  the  temperature  at  which  any  portion  of  the 
atmosphere  on  cooling  begins  to  precipitate  a  part  of  its 
water,  is  called  the  dew  point.  The  temperature  of  the 
dew  point  depends,  therefore,  upon  the  amount  of  water 
the  air  contains.  When  the  dew  point  is  above  the 
freezing  point  of  water  (32°  F.,  O°C. ),  the  precipitation 
is  in  the  form  of  dew  or  rain;  but  when  it  is  below  the 
freezing  point  of  water,  the  precipitation  is  in  the  form 
of  hoarfrost  or  snow.  One  more  principle  needs  to  be 
explained,  and  we  are  ready  to  understand 

207.  How  Frost  may  be  Foretold.  We  know  that 
sprinkling  the  floor  of  a  room  cools  the  air,  even  though 
the  water  used  is  no  cooler  than  the  air  of  the  room. 
This  is  because  the  air  in  taking  up  watery  vapor  ab- 
sorbs heat,  but  this  heat  is  set  free  again  when  the  watery 
vapor  is  precipitated.  A  steam  radiator  gives  out  heat 
because  the  steam  within  it  is  condensing  into  water.  It 
follows  that  when  the  dew  point  of  the  atmosphere  is 
reached,  a  very  considerable  amount  of  latent  heat  is 
given  off,  which  checks  the  fall  of  temperature.  The 
temperature  of  still  air,  therefore,  rarely  falls  much  below 
the  dew  point,  and  since  the  latter  at  any  given  tempera- 
ture depends  upon  the  amount  of  moisture  in  the  air,  if 


128 


Principles  of  Plant  Culture. 


we  have  an  instrument  capable  of  indicating  both  the 
temperature  and  the  moisture  of  the  air,  we  may  com- 
pute the  lowest  temperature  to  which  the  atmosphere 
will  be  likely  to  descend  during  any  given  night,  and 
thus  we  may  foretell  frost  with  some  degree  of  certainty. 
208.  The  Sling  Psychrometer  (psy- 
chrom'-e-ter)  enables  us  to  determine 
both  the  temperature  and  the  moisture 
of  the  air.  This  instrument  consists  of 
two  accurately-graduated  thermometers 
attached  to  a  board  or  case  (Fig.  60). 
The  bulb  of  one  thermometer  is  inclosed 
in  thin  muslin,  which  is  wet  just  before 
using  the  instrument  by  dipping  the  bulb 
in  rain  water,  or  is  connected  with  a 
small  vessel  containing  rain  water,  as 
shown.  By  means  of  a  string  attached 
to  the  board  or  case  at  the  end  opposite 
the  bulbs,  the  instrument  is  whirled 

FIG.  GO.  Sling  psy- 

chrometer,  used  to  about  in  the  air  a  few  times,  after  which 
the  thermometers  are  quickly  read  and 
the  difference  in  the  readings  noted.  When  the  air  is 
comparatively  dry,  evaporation  from  the  muslin  pro- 
ceeds rapidly,  and  on  account  of  the  heat  absorbed,  the 
wet  bulb  indicates  a  lower  temperature  than  the  dry  one. 
When  the  air  is  damp,  evaporation  is  slower,  and  the 
difference  between  the  readings  of  the  two  thermometers 
is  less.  In  saturated  air,  evaporation  ceases  and  the  two 
thermometers  read  alike.  By  means  of  the  following 
table,  the  dew  point  for  any  ordinary  out- door  tempera- 
ture and  atmospheric  humidity  during  the  growing  sea- 
son may  be  readily  determined. 


Injury  from  Cold  During  Growing  Period.        129 
Table  for  Computing  the  Dew  Point  in  Degrees  Fahrenheit. 


DRY 
BULB.             WET-BULB  DEPRESSION. 

. 

2 

3 

4 

5 

6 

7 

8 

9 

10 

II 

12 

13 

36 

32 

30 

27 

24 

21 

18 

13 

+8 

-1 

-12 

-32 

37 

31 

32 

29 

25 

21 

19 

15 

9 

+3 

-  7 

-23 

38 

35 

33 

30 

26 

23 

19 

17 

11 

+6 

-  3 

-16 

... 

... 

39 

36 

34 

31 

28 

24 

20 

16 

14 

8 

0 

-11 

-31 

40 

37 

35 

32 

29 

26 

22 

18 

12 

10 

+  3 

-  6 

-22 

4  1 

39 

36 

33 

30 

27 

23 

19 

14 

8 

-  6 

-  2 

-15 

42 

40 

37 

34 

31 

28 

25 

21 

16 

10 

+  3 

-  2 

-  9 

-29 

43 

41 

38 

35 

33 

30 

26 

22 

18 

13 

+  6 

-  3 

-  5 

-20 

44 

42 

39 

37 

34 

31 

27 

24 

20 

15 

9 

-  1 

-12 

-13 

45 

43 

40 

38 

35 

32 

29 

25 

21 

17 

11 

+  4 

—  7 

-27 

46 

44 

41 

39 

36 

33 

30 

27 

23 

19 

14 

+  7 

-  2 

-18 

47 

45 

43 

40 

37 

35 

32 

28 

25 

21* 

16 

10 

+  2 

-11 

48 

46 

44 

41 

39 

36 

33 

30 

26 

22 

18 

12 

+  5 

-  6 

49 

47 

45 

42 

40 

37 

34 

31 

28 

24 

20 

15 

+  8 

-  1 

50 

48 

46 

43 

41 

38 

36 

33 

29 

26 

22 

17 

11 

+  3 

5  1 

49 

47 

45 

42 

40 

37 

34 

31 

27 

23 

19 

13 

6 

52 

50 

48 

46 

43 

41 

38 

35 

32 

29 

25 

21 

16 

9 

53 

51 

49  • 

47 

44 

42 

40 

37 

34 

30 

27 

23 

18 

12 

54 

52 

50 

48. 

46 

43 

41 

38 

35 

32 

28 

24 

20 

15 

55 

53 

51 

49 

47 

45 

42 

39 

36 

33 

30 

26 

22 

17 

56 

54 

52, 

50 

48 

46 

43 

41 

38 

35 

32 

28 

24 

19 

57 

55 

53 

51 

49 

47 

45 

42 

39 

36 

33 

30 

26 

22 

58 

56 

54 

52 

50 

48 

46 

43 

41 

38 

35 

31 

28 

24 

59 

57 

55 

53 

51 

49 

47 

45 

42 

39 

36 

33 

29 

26 

60 

58 

56 

54 

52 

50 

48 

46 

43 

41 

38 

35 

31 

28 

61 

59 

57 

56 

54 

52 

49 

47 

45 

42 

39 

36 

33 

29 

62 

60 

58 

57 

55 

53 

51 

48 

46 

43 

41 

38 

35 

31 

209.  To  Compute  the  Dew  Point.  Find  the  wet-bulb 
depression  by  subtracting  the  wet-bulb  reading  from  that 
of  the  dry  bulb;  locate  this  in  the  top  line  of  the  table, 
and  find  the  dry-bulb  reading  in  the  left  hand  vertical 
column.  Opposite  the  dry  bulb  reading,  in  the  column 
headed  with  the  number  indicating  the  wet-bulb  depres- 
sion, is  the  dew  point  sought. 

Example:   Dry -bulb  reading 47  ° 

Wet-bulb  reading .40° 

Wet-bulb  depression. . : . .  7  ° 


130  Principles  of  Plant  Culture. 

Opposite  47  °,  in  the  left  hand  column,  and  under  7  in 
the  top  line,  we  find  28° — the  dew  point.  If  these 
readings  are  obtained  toward  sunset  on  a  clear,  still  even- 
ing, we  should  expect  frost,  because  the  dew  point  is  4 
degrees  below  the  freezing  point  of  water.  A  slight 
wind,  a  hazy  atmosphere,  or  a  few  fleecy  clouds  would 
render  frost  doubtful.  With  a  dry-bulb  reading  of  45° 
and  a  dew  point  of  25°,  a  killing  frost  might  be  expected. 

210.  Cold  Air  Drainage.     Warm  air,  being  lighter  than 
cold  air,  tends  to  rise,  while  the  colder  air  tends  to  fall. 
In  a  still  atmosphere,  therefore,  the  colder  air  accumu- 
lates in  the  lowest  places.     This  explains  the  familiar 
fact  that  hollows  and  valleys  are  colder  in  still  weather 
than  ridges  and  mountains.     In  a  falling  temperature 
and  in  the  absence  of  wind,  gentle  currents  of  the  colder 
air  tend  to  follow  the  water  courses,  which  •  explains  in 
part  why  frost  so  often  "goes  in  streaks." 

211.  Wind  Tends  to  Avert  Frost  because  it  prevents  the 
settling  of  the  colder  air  and  thus  keeps  the  temperature 
of  the  lower  strata  of  the  atmosphere  nearly  uniform. 

212.  Clouds,  Haze  and  Smoke  Tend  to  Avert  Frost  be- 
cause they  act  to  some  extent  like  a  blanket  in  prevent- 
ing the  radiation  of  heat  from  the  earth,  and  thus  check 
the  fall  in  temperature  (217). 

213.  The  Proximity  of  a  Body  of  Water  Tends  to  Avert 
Frost  because  the  water  cools  slower  than  the  air  and 
thus  checks  the  fall  in  temperature  of  the  atmosphere  in 
the  vicinity;  also  because  it  keeps  the  neighboring  at- 
mosphere moist,  thereby  raising  the  temperature  of  its 
dew  point  (206).     The  proximity  of  buildings  and  trees 
tends  to  avert  frost,  probably  because  these  objects  give 


Injury  from  Cold  During  Growing  Period.        131 

up  their  heat  gradually  and  thus  temper  the  surrounding 
atmosphere. 

214.  The  Localities  Most  Subject  to  Untimely  Frosts  are 

narrow  and  deep  valleys  inclosed  on  all  sides,  and  in- 
clined valleys  that  serve  as  channels  through  which  cold 
air  flows  to  lower  levels.  Partially -cleared  districts 
usually  suffer  more  from  frosts  than  those  fully  cleared, 
because  the  remaining  forests  obstruct  air  drainage. 

Marsh  areas  are  subject  to  frost,  because,  in  addition  to 
their  low  situation  as  compared  with  the  surrounding 
land,  their  luxuriant  vegetation  tends  to  cool  the  atmos- 
phere in  the  vicinity  by  exposing  a  large  radiating  sur- 
face and  promoting  abundant  evaporation. 

Valleys  surrounding  elevated  lakes  that  have  an  outlet 
through  which  the  colder  air  may  flow  to  lower  regions 
are  particularly  free  from  damaging  frosts.  The  valley 
of  Keuka  Lake,  in  west- central  New  York,  so  famous  for 
its  vineyards,  is  of  this  class. 

215.  Thermal   Belts.     In    some    elevated    districts    of 
mountainous  regions,  localities  of  greater  or  less  extent 
are  found  in  which  damaging  frosts  are  almost  unknown. 
These  have  been  called  thermal  belts,  and  their  freedom 
from  frost  is  explained  by  the  merging  of  the  warm  air, 
that  rises  somewhat  rarified  by  heat  from  the  lower  val- 
leys, with  the  atmosphere  of  the  more  elevated  region 
that  is  rarified  to  an  equal  extent  by  the  high  altitude. 
Thus  the  warm  air  ceases  to  rise,  but  lends  its  heat  to 
temper  the  climate  of  the  adjacent  mountains. 

216.  Liability  to  Damaging  Frost  Depends  Comparatively 
Little  upon  Latitude.    Within  the  tropics  are  areas  where 
frost  is  unknown  because  the  temperature  never  falls  to 


132  Principles  of  Plant  Culture. 

the  freezing  point.  But  in  localities  subject  to  frost,  the 
liability  of  damage  to  vegetation  from  this  cause  is  gov- 
erned more  by  cold  air  drainage  (210)  and  proximity  to 
water  than  by  latitude.  It  is  as  important  to  select  loca- 
tions for  peach  growing  with  reference  to  spring  frosts  in 
the  Carolinas  as  in  the  peach  belt  of  Michigan,  and 
favorable  locations  for  the  apple  in  Wisconsin  sometimes 
escape  damage  from  spring  frosts  in  seasons  when  the 
apple  crop  is  cut  off  by  frost  from  extensive  regions  of 
the  southern  states. 

217.  Methods  of  Preventing  Injury  by  Frost.  Any  non- 
conducting material  lying  between  the  earth  and  space, 
whether  spread  directly  upon  the  earth  or  at  a  consider- 
able height  above  it,  acts  as  a  blanket  to  intercept  the 
radiating  heat,  and  thus  prevents  in  a  measure  the  cool- 
ing of  objects  beneath  it.  For  this  reason,  straw,  muslin, 
or  other  non-conducting  material  spread  over  plants, 
usually  protects  them  from  frost. 

While  it  is  easy  to  protect  a  few  plants  from  frost  by 
covering  them  directly,  it  is  much  more  difficult  to  pro- 
tect large  plantations  in  this  manner.  Considerable 
plantings  of  the  strawberry  have  been  successfully  pro- 
tected from  frost  by  covering  the  rows  in  the  evening 
with  straw  or  marsh  hay,  and  where  these  materials  are 
convenient,  the  work  may  often  be  cheaply  and  quickly 
performed. 

Attempts  to  prevent  frost  on  a  large  scale  by  the  heat 
of  fires  or  by  burning  material  that  produces  much 
smoke  or  vapor,  have  not  been  sufficiently  successful  to 
commend  these  methods  for  general  application. 


Plants  as  Affected  by  Excessive  Water.  133 

SECTION  III.     THE  PLANT  AS  AFFECTED  BY  UNFAVOR- 
ABLE WATER  SUPPLY 

A  —  BY  EXCESSIVE  WATER 

218.  Excessive  Water  in  the  Soil  Destroys  the  Roots  of 

plants.  We  saw  that  oxygen  is  necessary  to  the  life  of 
roots  (90).  When  the  soil  cavities  are  filled  with  water, 
the  roots  are  soon  deprived  of  oxygen,  because  the  little 
oxygen  contained  in  the  water  is  soon  exhausted  (94). 
Smothering  and  decay  of  the  roots  follow.  Seeds  planted 
under  such  conditions  usually  fail.  The  soil  water  that 
is  most  useful  to  land  plants  is  that  which  remains  at- 
tached to  the  earthy  particles  after  percolation  has  nearly 
ceased  (capillary  water).  Such  water  is  well  aerated 
because  it  is  interspersed  with  cavities  that  are  filled 
with  air. 

In  the  open  ground,  the  remedy  for  excessive  soil 
water  may  usually  be  found  in  underground  drainage. 
But  the  same  trouble  often  occurs  in  potted  plants,  as 
the  result  of  too  compact  soil  or  too  copious  watering. 
The  expert  recognizes  this  condition  by  a  sour  odor  of 
the  soil,  by  lifting  the  pot,  or  by  tapping  the  pot  with 
his  knuckle.  If  the  soil  is  soggy,  the  weight  will  betray 
the  fact,  or  the  sound  given  out  by  the  pot  will  be  that 
of  a  compact  mass  instead  of  a  more  or  less  hollow  body, 
as  is  the  case  with  a  pot  of  well-aerated  soil.  To  remedy 
the  evil,  repot  the  plant  in  fresh  soil  of  a  proper  condi- 
tion of  moisture,  providing  abundant  drainage  at  the 
bottom  of  the  pot  (412). 

219.  Injudicious  Watering  is  perhaps  the  most  common 
cause  of  failure  in  growing  potted  plants.     The  amateur 


134  Principles  of  Plant  Culture. 

too  often  assumes  that  the  chief  need  of  the  plants  is  fre- 
quent watering,  and  so  gives  water  in  spoonful  doses  as 
the  surface  soil  of  the  pot  appears  dry,  without  observing 
the  state  of  the  soil  beneath.  The  roots  of  the  plants  in 
the  meantime  may  be  smothering  in  water- logged  soil  or 
starving  from  drought.  If,  owing  to  inexperience,  the 
condition  of  the  soil  cannot  be  determined  by  the  means 
above  noted,  the  soil  may  be  tipped  out  upon  the  hand 
without  materially  disturbing  the  roots  of  the  plant,  by 
reversing  the  pot  and  gently  striking  its  rim  on  the  edge 
of  the  bench  or  table.  The  real  condition  can  then  be 
readily  determined. 

220.  Copious  Waterings  at  Considerable   Intervals  are 
Preferable  to  frequent  slight  waterings.     It  should  never 
be  forgotten  that  air  is  as  essential  as  water  to  the  well- 
being  of  roots  (90),  and  that  the  soil,  however  porous, 
requires    occasional    ventilation  (94).     A    considerable 
quantity  of  water  poured  upon  the  surface  soil  of  a  pot- 
ted  plant,   in   passing   downward   not   only  thoroughly 
moistens  the  soil  particles,  but  acts  like  a  piston,  forcing 
the  vitiated  air  of  the  soil  cavities  ahead  of  it  and  out 
through  the  drainage  hole  at  the  bottom  of  the  pot,  while 
fresh  air  enters  from  above  as  the  surplus  water  passes 
out  beneath. 

221.  Rapidly-Growing   Plants  Require   More  Water  and 
are  less  liable  to  suffer  from  over- watering  than  slower- 
growing   ones.     During  the   rest  period    (173),   plants 
should  be  given  very  little  water. 

222.  Some  Species  Require  More  Water  than  Others. 
The  native  habitat  of  the  plant  is  a  partial  guide  to  the 
amount  of  water  needed.     Plants  native  to  arid  regions, 


Plants  as  Affected  by  Excessive  Water.  135 

as  the  cacti  and  those  from  treeless,  rocky  locations,  re- 
quire little  water  and  are  readily  destroyed  by  over- 
watering.  l '  Plants  with  narrow  and  tough  leaves,  espe- 
cially when  the  leaf-blade  is  vertically  placed,  do  not,  as 
a  rule,  like  much  water;  plants  with  broad,  leathery 
leaves  prefer  a  damp  atmosphere  to  great  moisture  at  the 
roots.  Succulent  plants  with  hard  epidermal  cells  (leaf- 
less Euphorbias,  succulent  Composites,  Aloes  and  Agaves), 
and  thin-leaved  plants  with  a  strong  wooly  covering  of 
hairs  are  further  examples  of  plants  which  require  very 
little  water."* 

223.  Excessive  Watering  sometimes  Produces  a  Drop- 
sical Condition  (oedema)  in  the  leaves  of  plants  under 
glass.     This  is  most  likely  to  occur  in  winter,  when  sun- 
light is  deficient,  especially  if  the  soil  is  kept  nearly  or 
quite  as  warm  as  the  air.     Water  accumulates  in  the 
cells,  abnormally  distending  their  walls  —  sometimes  even 
to  bursting.     An  unnatural  curling  of  the  leaves,  with 
yellow  spots  and  small  wart-like  excrescences  on  their 
surfaces,  are  some  of  the  symptoms  of  this  trouble.    Less 
water,  increased  light  and  reduced  bottom  heat  (362  a) 
furnish  the  remedy. 

Frenching,  a  disease  that  often  attacks  growing  tobacco 
on  excessively -wet  clay  soils  may  be  due  to  the  undue 
absorption  of  water  by  the  roots.  The  leaves  of  affected 
plants  grow  narrow,  and  are  thick,  fleshy  and  wrinkled. 
If  the  plants  are  pulled  sufficiently  to  break  the  tap-root, 
before  the  disease  has  progressed  too  far,  they  often 
recover. 

224.  Water-Sprouts   (sap -sprouts,  gormands)  on  fruit 
trees  are  sometimes  due  to  an  excess  of  water  in  the  soil. 


*  Sorauer,  Physiology  of  Plants,  p.  207. 


136  Principles  of  Plant  Culture. 

These  thick,  rapidly-growing  shoots,  with  remote  leaves 
and  poorly- developed  buds,  growing  from  the  main 
branches  of  unthrifty  fruit  trees,  are  most  common  on 
undrained,  heavy  soils.  They  rarely  produce  much  fruit, 
but  tend  to  rob  the  bearing  branches  of  light  and  nourish- 
ment. They  usually  continue  to  grow  late,  and  in  severe 
winters  are  often  injured  by  cold.  Water-sprouts  may 
also  result  from  over-pruning  and  from  inj  ury  of  the  tree 
by  cold,  but  in  the  absence  of  these  conditions  they  sug- 
gest the  need  of  drainage. 

225.  Fruits  and  Vegetables  often  Crack  from  Excessive 
Moisture,  either   through  too  much   absorption   by   the 
roots  or  by  direct  absorption  through  the  skin.     Crack- 
ing is  most  frequent  after  heavy  rains  following  drought. 
Apples,  tomatoes,  melons,  carrots,  kohl-rabi,  cabbage  and 
the  potato  tuber  are  subject  to  it.     On  wet  soils,  drainage 
may  largely  remedy  the  evil.     The  selection  of  varieties 
least  subject  to  cracking  is  also  helpful,  especially  in 
melons  and  tomatoes  which  often  crack  in  comparatively 
dry  weather.     In  these  cases,  the  cracking  is  probably 
due  to  an  unequal  maturing  of  the  fruit  which  causes 
certain  parts  to  grow  faster  than  others.     The  bursting 
of  cabbage  heads  is  due  to  the  excessive  absorption  of 
water  by  the  roots.     To  prevent  it,  we  start  the  plants 
by  pulling  on  the  stem  sufficiently  to  break  a  part  of  the 
roots. 

226.  Knobby  Potatoes  are  caused  by  a  wet  period  fol- 
lowing a  drought  during  the  ripening  season.     Parts  of 
the  plant  that  are  still  alive,  stimulated  by  abundant 
water,  resume  growth.     But  since  cell  division  is  possi- 
ble only  in  the  parts  containing  protoplasm,  the  mature 


Plants  as  Affected  by  Insufficient  Water.          137 

cells  of  the  tuber  can  no  longer  divide,  hence  growth  is 
limited  to  the  younger  parts,  i.  e.,  the  vicinity  of  the 
buds  (eyes),  and  these  therefore  grow  out  into  unshapely 
protuberances.  The  knob  consumes  a  part  of  the  starch 
previously  stored  in  the  tuber  from  which  it  grows, 
hence  knobby  potatoes  are  poorer  in  food  value  than 
smooth  ones  of  the  same  lot. 

Certain  varieties  of  potato  are  more  disposed  to  knob- 
biness  than  others.  In  varieties  normally  free  from  it, 
the  planting  of  knobby  seed  tubers  probably  does  not 
tend  to  increase  the  inclination  to  knobbiness. 

227.  Excessive  Moisture  in  the  Air  is  Injurious  to  plants, 
since  it  tends  to  hinder  normal  transpiration  (75)  and 
favors  the  growth  of  certain  fungous  parasites  (321).    In 
the  greenhouse,  we  control  the  atmospheric  moisture  by 
ventilation  and  care  in  the  use  of  water.     Out  of  doors, 
we  guard  against  excessive  moisture  in  the  air  by  giving 
plants  sufficient  room  to  favor  the  circulation  of  air  be- 
tween them.     The  latter  precaution  is  especially  import- 
ant in  orchard  planting,  since  several  fungi  that  prey 
upon  fruit  trees,  as  the  apple  scab  (328)  and  pear  blight 
(323),  flourish  in  a  damp  atmosphere. 

B  — THE  PLANT  AS  AFFECTED  BY  INSUFFICIENT  WATER 

228.  Insufficient  Moisture  in  the  Air  Causes  Excessive 
Transpiration  (75),  which  reduces  the  tension  of  the  cell- 
walls  and  thus  retards  growth  (63).    It  also  tends  to  clog 
the  leaves  with  useless  mineral  matters,  causing  their 
premature  death  (126),  and  favors  the  development  of 
certain   furgous  parasites.      The  effects  of  insufficient 
moisture  in  the  air  are  often  very  noticeable  upon  plants 


138  Principles  of  Plant  Culture. 

kept  in  living-rooms  in  winter.  »Such  plants,  especially 
when  few  in  number,  rarely  make  satisfactory  growth 
and  the  lower  leaves  continually  perish.  Moistening  the 
air  by  evaporating  water  in  the  room  or  setting  the  pots 
containing  the  plants  upon  a  table,  covered  with  moist 
sand  usually  remedies  the  trouble. 

Insufficient  moisture  in  the  open  air  rarely  occurs  un- 
less there  is  also  a  dearth  of  water  in  the  soil. 

229.  Insufficient  Moisture  in  the  Soil  Retards  Growth 
both  by  reducing  the  tension  of  the  cell-walls  (63),  and 
by  lessening  the  supply  of  food  from  the  soil.     The  ten- 
dency of  drought  is,  therefore,  to  starve  the  plant. 

Plants  that  have  been  subjected  to  insufficient  water 
from  the  beginning  usually  suffer  less  from  drought  than 
those  previously  well  watered,  because  their  root  system 
has  become  more  extensively  developed  (112  J. 

230.  Drought   tends  to  Hasten    Maturity,  especially  in 
annual  plants,  since  it  favors  flowering  (135).     Lettuce, 
spinach,  rhubarb  etc.,  "run  to   seed"  earlier  if  insuf- 
ficiently supplied  with  water.     Potatoes  usually  ripen 
earlier  in  dry  seasons  than  in  wet  ones.     If  the  drought  is 
sufficiently  severe  or  sufficiently  prolonged,  diminution 
or  failure  of  seedage  results. 

231.  Toughness  of  Plant  Tissues  Results  from  Drought. 
The  crispness  and  tenderness  that  give  quality  to  salad 
vegetables,  as  celery,  lettuce,  radish  etc.,  due  to  a  dis- 
tended condition  of  their  cell-walls,  is  largely  wanting 
when  the  water  supply  during  growth  has  been  insufficient. 

Insufficient  water  during  growth  injures  the  quality  of 
tobacco.  Leaves  thus  affected  have  a  peculiar  spotted 
appearance  when  cured,  and  do  not  u  sweat"  properly. 


Plants  as  Affected  by  Insufficient  Water.          139 

232.  Crumbling  of  the  Surface  Soil  (cultivation)  tends 
to  Prevent  Drought,  since  it  greatly  lessens  the  points  of 
contact  in  the  soil  particles,  and  thus  interferes  with  the 
rise  of  the  soil  water  by  capillary  attraction  to  the  sur- 
face where  evaporation  chiefly  occurs.     An  air- dry  sur- 
face layer  of  crumbled  soil  also  tends  to  prevent  evapor- 
ation by  keeping  the  soil  cooler  beneath.     A  puddled 
crust  on  the  surface  of  the  soil,  as  is  formed  by  rain  on 
soils  containing  clay,  tends,  on  the  other  hand,  to  restore 
capillary  action  and  thus  to  promote  evaporation.    Some 
gardeners  cultivate  their  hoed  crops  as  soon  as  possible 
after  rains  for  the  main  purpose  of  breaking  this  crust 
and  thus  stopping  the  capillary  action. 

Cultivation  is  also  beneficial  by  aerating  the  soil  (94). 
The   roots  of  plants   should   never  be  forgotten   nor 
ignored  in  cultivating  crops  (110). 

233.  Mulching  tends  to  Prevent  Drought  by  interposing 
a  layer  of  poor- conducting  material  between  the  ground 
and  the  sun's  rays.     This  keeps  the  surface  soil  cooler 
and  so  checks  evaporation. 

The  best  mulching  material  is  the  one  that  conducts 
both  heat  and  moisture  slowest.  Straw,  marsh  hay, 
leaves,  manure,  shavings,  sawdust,  spent  tan  and  sand 
are  all  useful  for  mulching,  but  the  first  four  named  are 
generally  preferable  to  the  others,  especially  if  free  from 
weed  seeds. 

Growing  plants  tend  to  dry  the  soil  because  the  root- 
hairs  continually  draw  in  soil  water  and  force  it  into  the 
leaves  (102)  where  it  passes,  off  by  transpiration  (75). 
Weeds,  therefore,  rob  crops  of  moisture  (336). 

234.  Irrigation,  i.  e.,  the   extensive  watering  of  out- 
door plants,  is  the  final  remedy  for  drought.    It  is  neces- 


140  Principles  of  Plant  Culture. 

sary  to  plant  culture  in  arid  regions,  and  may  be  profit- 
ably employed  at  certain'  times  in  the  great  majority  of 
seasons  in  many  localities  where  the  annual  rainfall  would 
satisfy  the  needs  of  crops,  were  it  more  uniformly  dis- 
tributed. 

235.  Drying  beyond  a  certain  limit  Kills  Plant  Tissues 
by  destroying  in  part  their  power  for  conducting  water. 
Care  should  be  used  to  retain  the  normal  moisture  in 
buds  (394),  cuttings  (358),  and  cions  (386)  and  in  the 
roots  of  plants  lifted  for  transplanting. 

SECTION  IV.    PLANTS  AS  AFFECTED  BY  UNFAVORABLE 

LIGHT 

A  —  BY  EXCESSIVE  LIGHT 

236.  The  Unobstructed  Rays  of  the  Sun  are  often  Injur- 
ious to  young  seedlings,  to  unrooted  cuttings  and  to  plants 

recently    transplanted. 

'^\rf//////////$////ff£~  tt  is  diffieult  to  ^p*' 

rate  ^e  influences  of 
light  and  heat,  since 
the  heat  is  usually 
greatest  where  the  sun' s 
rays  are  brightest;  but 
bright  light  probably 
stimulates  transpiration 
tor  shading  (75)  independent  of  heat 

cold-frames  and  tender  plants  in  the  open   and    thus    tends    to   CX- 

ground.   (After  Bailey).  haust  the  plant  of  water. 

Various  devices  are  used  to  break  the  force  of  the  solar 
rays.  In  out-door  culture,  screens  of  lath  (Figs.  61,  62)r 
cloth  or  brush  (Fig.  63)  are  often  placed  over  beds  con- 


Plants  as  Affected  by  Excessive  Light. 


141 


taining  cuttings  or  tender  seedlings,  as  of  many  cone- 
bearing  trees.     Cuttings  in  the  nursery  may  be  shaded 

by  supporting  a  board 
over  the  row,  on  short 
stakes  (Fig.  64),  so  as  to 
protect  them  during  the 
warmer  hours  of  the  day. 

FIG.  62.    Shed  screen  built  of  three-inch-   Shingles,  flower-pots  OF 
wide  slats,  for  shading  tender  plants  and   ,  lpov<*»    **  nf 

for  storing  pots  and  boxes  of  slow-germi-   iaige  gre  /aVCS,  a 

nating  seeds.    (After  Bailey).  the  burdock,  are  Useful 

for  shading  plants  of  the  cabbage,  tomato  etc. 


FIG.  63.  Brush  screen,  for  shading  tender  plants  in  the  open  ground. 
{After  Bailey). 

In  culture  under  glass,  the  glass  is  often  thinly  washed 
with  lime  or  clay  to  render  it  partially  opaque,  or  lath 
screens  are  used  either  above  or  below  the  glass.  On 


FIG.  '64.    Board  shade  for  recently-set  plants,  or  for  cuttings  not  yet  rooted. 

greenhouse  benches,  sheets  of  thin  paper  or  light  cloth 
screens  are  useful  for  shading  cuttings,  recently-planted 
seedlings  and  germinating  seeds. 

Shading  should  never  be  so  put  on  as  to  prevent  a  free 
circulation  of  air  about  the  plants. 


142  Principles  of  Plant  Culture. 

A  shade  that  obstructs  only  a  part  of  the  rays  of  sun- 
light at  a  time,  as  does  the  lath  or  brush  screen,  is  gen- 
erally preferable  to  one  that  continuously  breaks  the  force 
of  all  the  rays,  as  does  paper  or  whitewashed  glass. 

237.  Cauliflower  Heads  should  be  Sheltered  from  Sun- 
light to  prevent  the  formation  of  chlorophyll  in  their 
cells  (40),  which  darkens  their  color  and  gives  them  a 
strong  flavor.     The  leaves  surrounding  the  head  may  be 
tied  about  it  or  broken  over  so  as  to  shade  it  from  direct 
sunlight. 

B  —  PLANTS  AS  AFFECTED  BY  INSUFFICIENT  LIGHT 

238.  Insufficient  Light  is  a  Frequent  Cause  of  Abnormal 

Development  in  plants.     Some  of  its  effects  are 

a  —  Excessive  elongation  of  the  cells  of  the  internodes 
(76),  causing  the  plants  to  "draw  up"  or  grow  spindling. 

b  —  Deficient  formation  of  chlorophyll  (58),  giving 
the  foliage  a  pale-green,  yellowish  or  whitish  tint,  and 
resulting  in 

c  —  Lessened  food  formation,  causing  reduced  leaf  de- 
velopment and  deficient  vascular  bundles  (68). 

d  —  Reduced  transpiration  tending  to  watery,  weak  - 
celled  growth. 

e  —  Weakening  of  the  color  and  flavor  of  some  fruits, 
as  the  apple  and  strawberry. 

f — Preventing  pollination  (151). 

g  —  Reducing  fruitful  ness. 

Owing  to  these  causes,  plants  grown  in  deficient  light 
have  tall,  slender,  weak  stems,  few,  small,  pale  leaves  and 
scantv  roots  and  are  often  unfruitful.*  Such  plants, 


*  Tomato  plants  grown  in  winter  on  poorly-lighted  benches  are  often 
unfruitful  even  when  they  grow  well  and  bloom  freely. 


Plants  as  Affected  by  Insufficient  Light.  143 

though  of  species  that  normally  grow  upright,  are  often 
unable  to  stand  erect  without  support.  Familiar  ex- 
amples are  cabbage  and  tomato  plants  that  lop  over  when 
planted  out,  because  grown  in  the  seed-box  to  transplant- 
ing size  without  "  pricking  off"  (106);  and  grain  sown 
too  thickly  on  rich  ground,  that  falls  (lodges)  before 
maturity. 

239.  Too  Close  Planting  Causes  Deficient  Light  and  all 
the  resulting  evils.     Indian  corn  grown  too  thickly  does 
not  ear  well  and  is  lacking  in  nutritive  qualities;  straw- 
berry plants  grown  too  closely  do  not  fruit  well  and  the 
fruit  lacks  flavor  and  firmness;  nursery  trees  grown  too 
closely  are  slender-stemmed,  deficient  in  foliage  and  have 
poorly -developed  roots.     A  rule  to  govern  distance  in 
planting  has  already  been  given  (123). 

When  a  slender  and  flexible  growth  is  desired,  as  in 
trees  grown  for  hoop  poles,  or  willows  for  wicker-work 
and  tying,  a  certain  amount  of  crowding  is  advisable. 

240.  Weeds  Cause  Deficient  Light  in  low-growing  crops 
as  strawberries,  dwarf  beans,  potatoes  etc.,  and  also  tend 
to  rob  the  plants  of  food  and  moisture.     They  are,  there- 
fore, decidedly  injurious  (336). 

241.  Plants  Under  Glass  are  Especially  Liable  to  Suffer 
from  Deficient  Light,  because  the  walls  and  sash  bars  of 
the  structure  necessarily  intercept  a  considerable  part  of 
the  solar  rays.     The  roofs  of  glass  houses   should  be 
formed  of  large  lights  of  glass,  with  the  smallest  possible 
sash  bars,  and  the  benches  should  be  arranged  to  bring 
the  plants  as  near  to  the  glass  as  possible. 

242.  The  Electric  Light  has  been  found  useful  as  a  sup- 
plement  to   the   scanty  sunlight  of  short,  early- winter 
days,  in  forcing  certain  vegetables  and  flowers. 


144 


Principles  of  Plant  Culture. 


243.  Insufficient  Pruning  Prevents  the  formation  of 
Fruit-Buds  in  orchard  trees  by  restricting  light  and  thus 
reducing  food  formation  (59).  Com- 
pare Fig.  65,  which  shows  a  fruit 
branch  of  the  apple  tree  grown  where 
exposed  to  abundant  sunlight,  with 
Fig.  66,  showing  one  grown  in  partial 
shade.  * 

244.  Blanching  of  certain  vegetables, 
as  celery,  endive,  cardoon  and  sea  kale 
is  practiced  by  gardeners  to  render 
them  more  tender  and  delicate.     It  is 
effected  by  excluding  the  light  from 
the  parts   desired   for  use,  until  the 
chlorophyll  (58)  mostly  disappears,  by 
banking  the  plants  with  earth  or  in- 
closing them  in  paper  or  in  drain- tile. 
Very  close  planting  is  sometimes  prac- 
ticed to  promote  blanching. 

SECTION  Y.     PLANTS  AS  AFFECTED 
BY  UNFAVORABLE  WIND 

A  — BY  EXCESSIVE  WIND 

245.  Damage   to   trees    and    other 
plants  by  excessive  wind  is  too  famil- 
iar to  need  notice,  except  to  suggest 
preventive  measures. 

a  —  The  premature  blowing  off  of 
fruits  may  be  in  a  measure  prevented 
by  planting  fruit  trees  where  they  are 
more  or  less  sheltered  from  prevailing 
wrinds  by  shade  trees,  buildings,  forests 


FIG.  65.        FIG.  66. 

Fig.  65.  Fruit  branch 
of  apple  grown  in 
abundant  light. 

Fig.  66.  Another 
grown  in  partial  shade. 

F,  fruit-buds;  L,  leaf- 
buds.  (After  Kinney). 


*  See  Bulletin  No.  37,  Rhode  Island  Agricultural  Experiment  Station. 


Plants  as  Affected  by  Unfavorable  Wind.          145 

or  elevations  of  land.  Orchards  may  be  in  part  pro- 
tected by  planting  a  wind-break  on  the  windward  side 
(204). 

b  —  Shade  trees  in  exposed  situations  should  be  headed 
low,  and  the  head  should  be  formed  of  numerous  branches. 
The  higher  the  head,  the  more  it  is  exposed  to  wind  and 
the  greater  is  the  leverage  upon  the  trunk.  Several 
small  branches  are  better  able  to  bear  the  tempest  than 
a  few  larger  ones. 

Shade  trees  for  exposed  situations  should  be  of  species 
not  likely  to  be  deformed  by  wind.  Certain  trees,  as  the 
white  maple,*  often  develop  one-sided  if  planted  where 
exposed  to  prevailing  winds,  while  others,  as  the  sugar 
maple  f  and  Norway  maple  J  are  not  thus  affected. 

B  —  PLANTS  AS  AFFECTED  BY  INSUFFICIENT  WIND 

246.  Insufficient  Wind    Promotes  the  development  of 
certain  Fungous  Parasites  (321)  by  favoring  an  exces- 
sively moist  atmosphere.     Orchards  too  closely  planted 
or  surrounded  by  wind  barriers  suffer  more  from  fungous 
attacks  than  those  having  freer  circulation  of  air  between 
the  trees. 

247.  Insufficient  Wind  Promotes  Damage  from  Frost  by 
permitting  cold  air  to  settle  in  the  lower  places  (210). 

On  these  accounts,  gardens  and  fruit  plantations  should 
not  be  entirely  surrounded  by  wind  barriers. 

248.  Pollination  (151)  is  Dependent  upon  Wind  in  many 
plants,  as  the   coniferous  trees,  oaks,  elms,  birches  and 
sedges;  but  as  the  pollen  of  such  plants  is  very  light, 
their  fruitfulness  is  not  often  much  restricted  by  insuf- 
ficient wind. 


*  Acer  dasyearpum.  f  Acer  saccharinum.  J  A cer  platanoides. 


146  Principles  of  Plant  Culture. 

SECTION   VI.     PLANTS   AS   AFFECTED    BY    UNFAVOR- 
ABLE FOOD  SUPPLY 

We  saw  that  water  is  the  most  important  constituent 
of  plant  food  (63)  and  we  have  already  considered  the 
plant  as  affected  by  water  supply  (Section  III).  But  a 
proper  supply  of  the  other  essential  food  constituents  is 
only  second  in  importance  to  that  of  water. 

A  — PLANTS  AS  AFFECTED  BY  EXCESSIVE  FOOD 

249.  Excessive  food  is  not  the  extreme  that  we  have 
most  to  fear,  since  natural  soils  are  rarely  excessively 
fertile,  and  we  can  only  make  them  so  by  costly  methods. 
Indeed,  nearly  all  the  constituents  of  plant  food  may  be 
present  in  excess  of  plants'  requirements  without  work- 
ing harm.     Nitrogen,  however,  which  aside  from  water 
is  the  most  potent  food  constituent,  must  be  used  with 
some  discretion. 

250.  Excessive  Nitrogen  Stimulates  Growth  at  the  ex- 
pense of  flowers,  seed  and  fruit.     In  crops  grown  for 
these  parts,  therefore,  fertilizers  rich  in  nitrogen  must  be 
used  with  caution.     Apple,  pear  and  quince   orchards 
liberally  manured  with  such  fertilizers  produce  an  ex- 
cessive, over- succulent  growth  of  wood,  that  is  subject 
to  blight  and  winter  injury  and  forms  comparatively  few 
fruit  buds.     Grain  under  similar  conditions  forms  long, 
weak  straw,  with  poorly-filled  heads.     Grape  vines  on 
over- manured  ground  produce  excessive  wood  with  few 
and  late- ripening  bunches. 

There  is  little  danger  of  over- manuring,  however,  with 
crops  grown  for  parts  other  than  flowers,  fruit  or  seed,  so 


Plants  as  Affected  by  Insufficient  Food.  147 

long  as  stable  manure  is  used  (252).  But  the  more  con- 
centrated animal  manures,  as  those  from  poultry  and  the 
hog,  the  chemical  compounds  of  nitrogen,  as  nitrate  of 
soda  and  sulfate  of  ammonia  (262),  and  the  so-called 
11  high-grade"  commercial  fertilizers  must  be  used  with 
caution,  as  they  may  destroy  the  plants  if  applied  in 
excess. 

B  —  PLANTS  AS  AFFECTED  BY  INSUFFICIENT  FOOD 

251.  It  is  difficult  to  separate  the  effects  of  a  lack  of 
food  from  those  of  a  lack  of  water,  since  the  food  is 
mainly  conveyed  to  the  plant  in  the  soil  water  (63).    But 
even  with  a  proper  water  supply,  if  one  or  more  of  the 
requisite  food  materials  is  lacking  (61),  a  normal  plant 
structure  cannot  be  built  up.     An  excess  of  one  food  sub- 
stance cannot  compensate  for  the  lack  of  another,  except  in 
a  few  instances. 

252.  Insufficient  Food  Dwarfs  the  Plant  in  all  its  parts. 
A  dwarfing  of  the  size  of  the  plant  body  may  occur,  how- 
ever, without  a  corresponding  dwarfing  of  the  seed  pro- 
duct; hence  plants  may  often  bear  their  maximum  amount 
of  seed  or  fruit  without  attaining  their  maximum  dimen- 
sions.    Plants  grown  for  seed  or  fruit  are,  therefore,  less 
likely  to  be  restricted  in  yield  by  insufficient  food  than 
those  grown  for  their  leaves,  stems,  roots  or  tubers.    The 
cereals,  for  example,  produce  well  on  land  not  sufficiently 
fertile  to  yield  equally  good  crops  of  tobacco,  cabbage, 
celery,  lettuce  or  potatoes.     But  with  a  sufficient  restric- 
tion of  food,  the  seed  product  will  suffer  diminution  or 
be  wholly  cut  off. 

253.  Crop-Growing  Tends  to  Reduce  Plant  Food  in  the 
soil  in  proportion  as  the  fertilizing  components  of  the 


148  Principles  of  Plant  Culture. 

crops  are  removed  from  the  land  and  are  not  returned  to 
it,  directly  or  in  equivalent.  Fortunately,  considerable 
plant  food  is  constantly  being  liberated  by  the  disinte- 
gration and  decay  of  rock  or  soil  materials,  or  is  being 
deposited  from  the  atmosphere  in  rain  and  snow,  so  that 
it  is  impossible  to  exhaust  the  soil  of  plant  food,  even 
with  the  most  improvident  culture.  But  the  cultivator 
should  aim  at  the  largest  returns  from  his  soil,  and  these  are 
impossible  without  restoring  certain  materials  that  con- 
tinued crop-removal  invariably  reduces  below  the  limit 
of  profitable  yields. 

254.  The   Food   Elements   Most  Likely  to  be  Deficient, 
when  plants  are  properly  supplied  with  water,  are  nitro- 
gen, phosphorus  and  potassium.     These  are  all  liberated  in 
greater  or  less  quantities,  when  vegetable  or  animal  ma- 
terial (organic  matter)  decays  in  the  soil;  hence  all  such 
material  has  more  or  less  value  as  fertilizers.     But  we 
need  not  wholly  depend  upon  refuse  organic  matter  for 
fertilizers,  since  the  leguminous  plants  add  nitrogen  to 
the  soil  (260),  and  compounds  of  nitrogen,  phosphorus 
and  potassium  may  often  be  purchased  in  artificial  fertil- 
izers at  prices  that  place  them  within  the  reach  of  the 
cultivator. 

255.  Nitrogen  is  the  Most  Important  Fertilizing  Element 
because  it  is  liberated  in  smallest  amount  by  rock  decay 
and  is  most  expensive  in  the  market.    Nitrogen  is  chiefly 
used  by  plants  in  the  form  of  nitrates,  i.  e.,  in  combina- 
tion with  certain  other  substances  as  soda,  potash,  lime, 
magnesia  and  iron.     Ammonia,  which  is  a  gaseous  com- 
pound of  nitrogen  and  hydrogen,  is  also  used  to  some 
extent   by   plants.     Free   nitrogen,  the   most  abundant 


Plants  ax  Affected  by  Insufficient  Food.  149 

constituent  of  the  air,  plays  no  direct  part  in  plant  nu- 
trition (260). 

256.  The  Sources  of  Nitrates  in  the  Soil  are 

a  —  Nitrification  (nit-ri-fi-ca'-tion),  by  which  the  nitro- 
gen contained  by  organic  matter  and  ammonium  sulfate 
in  the  soil  is  changed  to  nitric  acid  through  the  agency 
of  microscopic  plants  (bacteria).  The  nitric  acid  thus 
formed  combines  with  certain  substances  (bases')  in  the 
soil,  as  potash  and  lime,  forming  nitrates  (255). 

b  —  Symbiosis  (sym-bi-o'-sis)  on  the  roots  of  legumin- 
ous crops,  through  which  atmospheric  nitrogen  is  changed 
to  nitric  acid  (260,  113). 

c  —  Deposits  from  the  atmosphere  in  rain  or  snow  (261). 

d  —  Ammonium  salts  or  nitrates  applied  to  the  soil  (262). 

257.  The  Conditions  Affecting  Nitrification  are  similar 
to  those  affecting  plant  life  in  general,  since  nitrification 
results  from  plant  life.     As  it  takes  place  below  the  sur- 
face of  the  soil,  it  is  favored  by  the  same  conditions  that 
favor  the  root  growth   of  land  plants,  viz.,  aeration, 
warmth  and  moisture.     In  general,  it  is  active  during 
the  growing  season,  but  at  a  standstill  during  the  dor- 
mant period.     It  does  not  proceed  rapidly  in  spring  un- 
til the  soil  has  become   sufficiently  warm  to  promote 
active  root  growth. 

Nitrification  also  releases  the  other  food  materials  con- 
tained by  organic  matter  (93). 

258.  Soil  Aeration  Promotes  Fertility  by  favoring  nitri- 
fication.    Thus  cultivation  and  drainage  (of  heavy  soils) 
not  only  directly  promote  the  growth  of  plants  by  assist- 
ing aeration  (94),  but  they  actually  increase  plant  food. 
Early  plowing  in  spring  promotes  nitrification  by  favor- 


150  Principles  of  Plant  Culture. 

ing  warming  of  the  soil.  Cultivation  in  dry  weather 
further  promotes  plant  nutrition  by  preventing  the  accu- 
mulation of  soluble  plant  food  in  the  dry  surface  soil, 
where  it  is  deposited  above  the  reach  of  roots  through 
evaporation. 

259.  Partially-Decomposed   Organic  Manures  Act   More 
Promptly  than  fresh  ones,  because  nitrification  has  already 
commenced  in  these  materials. 

260.  Leguminous  Plants  Enrich  the  Soil  with  nitric  acid 
(256),  which  is  formed  from  atmospheric  nitrogen  in  the 
tubercles  on  their  roots  through  the  agency  of  micro- 
scopic plants  (113).     Even  when  a  part  of  these  crops 
is  removed  from  the  land,  as  when  clover  is  harvested 
for  hay  or  peas  for  their  seed,  the  land  is  richer  in  nitro- 
gen than  before  the  crop  was  planted.     The  principal 
leguminous  crops  are  the   clovers,  peas,  beans,  lentils, 
sanfoin,  vetches,  alfalfa,  lupine   and   certain  species  of 
Lathyrus.     Highly  valuable  as  are  these  crops  for  the 
nitrogen  they  leave  in  the  soil,  it  should  be  remembered 
that  they  do  not  contribute  phosphoric  acid  or  potash, 
and  hence  must  not  be  wholly  depended  upon  for  soil 
fertility  (263,  264). 

Leguminous  plants  are  supplied  with  nitrogen  by  the 
micro-organisms  in  their  roots  (113),  and  hence  do  not 
require  this  element  in  fertilizers. 

261.  Rain  and  Snow  Add  Nitrogen  to  the  Soil  in  small 
quantities,  both  as  nitric  acid  and  ammonia,  which  they 
have  taken  from  the  air,  but  the  amounts  thus  added, 
while  useful  to  plants,  are  not  under  our  control. 

262.  Nitrogen  may  be  Purchased  for  fertilizing  pur- 
poses as  sodium  nitrate  (nitrate  of  soda,  Chili-saltpeter), 


Plants  as  Affected  by  Insufficient  Food.  151 

ammonium  sulfate  (sulfate  of  ammonia),  and  in  organic 
materials.  The  former  is  available  as  plant  food  when 
it  is  dissolved  in  the  soil  water.  It  is  best  applied 
immediately  before  the  planting  of  a  crop  or  in  small 
quantities  at  intervals  during  growth,  since  it  is  in  dan- 
ger of  being  washed  out  of  the  soil  in  drainage  water. 
Sodium  nitrate  is  especially  useful  for  garden  crops 
started  early  in  spring,  when  the  soil  is  too  cool  for  active 
nitrification  (256).  The  surface  soil  is  apt  to  be  poor  in 
nitrates  in  spring,  because  they  are  often  washed  down 
by  the  autumn  and  winter  rains. 

Ammonium  sulfate  is  changed  to  nitrates  in  the  soil 
before  it  is  used  by  plants,  and  hence  is  less  prompt  in 
its  action  than  sodium  nitrate.  It  is  more  tenaciously 
held  by  the  soil  than  sodium  nitrate  and  is  therefore  less 
likely  to  be  lost  by  washing. 

263.  Phosphorus  is  used  by  plants  in  the  form  of  solu- 
ble phosphoric  acid,  which  exists  in  the  soil  in  combina- 
tion with  lime,  iron  and  alumina,  as  phosphates  of  these 
substances.     It  may  be  purchased  in  the  form  of  mineral 
phosphate  of  lime,  ground  bone,  wood  ashes,  odorless 
phosphates  etc.     The  first  two  are  insoluble  in  water  un- 
less treated  with  a  strong  acid,  when  they  are  known  as 
acid  phosphate  or  superphosphate.     Phosphoric  acid  is  not 
readily  washed  out  of  the  soil,  even  in  its  soluble  form. 

264.  Potassium  is  used  by  plants  in  the  form  of  potash, 
i.  e. ,  potassium  combined  with  oxygen.     Potash  exists  in 
the  soil  mainly  in  combination  with  chlorin  (chlorid  or 
muriate  of  potash),  with  sulfur ic  acid  (sulfate  of  potash), 
or  with  nitric  acid  (nitrate  of  potash).     All  these  forms 
of  potash  are  freely  soluble  in  water  and  are  immediately 


152  Principles  of  Plant  Culture. 

available  as  plant  food.  Xitrate  of  potash  (saltpeter)  is 
a  most  valuable  fertilizing  material,  since  it  contains 
both  potash  and  nitrogen,  but  unfortunately  its  price  is 
too  high  to  permit  its  use  for  this  purpose.  The  muriate, 
either  pure  or  in  crude  form  (kainit),  and  sulfate  may, 
on  the  other  hand,  be  purchased  at  reasonable  prices. 
The  sulfate  is  considered  preferable  for  tobacco  and  pota- 
toes as  it  is  thought  to  produce  a  better  quality  of  pro- 
duct. The  muriate  acts  more  promptly  than  the  sulfate, 
however. 

265.  Wood  Ashes  are  a  Valuable    Fertilizer,  especially 
when  unleached,  as  they  contain  both  potash  and  phos- 
phoric acid.     In  leaching,  the  potash  is  mostly  washed 
out,  but  the  phosphoric  acid  is  largely  retained.     Ashes 
contain  no  nitrogen. 

266.  Farm  and  Stable  Manures  should  be  the  first  de- 
pendence of  the  cultivator.     Aside  from  these,  legumin- 
ous crops  (260)  are  undoubtedly  the  cheapest  source  of 
nitrogen  for  the  farm,  and  with  unleached  wood  ashes, 
furnish  all  the  needed  fertilizing  ingredients  for  grain 
crops  grown  in  rotation.     For  garden  crops,  however,  if 
sufficient  stable  manure  can  not  be  obtained,  more  nitro- 
gen may  often  be  profitably  used  than  can  be  furnished 
by  leguminous  crops,  hence  for  these,  commercial  fertil- 
izers may  often  be  added  with  advantage. 

267.  Crops  Suggest  Their  Own  Needs  to  some  extent,  so 
long  as  they  are  not  suffering  from  drought.     As  a  rule, 
a  lack  of  nitrogen  is  indicated  by  pale- green  foliage  or 
small  growth  of  leaf  or  stalk.     Excess  of  nitrogen  is 
indicated  by  very  large  growth  of  leaf  or  stalk,  with 
imperfect  bud-,  flower-  and  fruit  development.     Lack  of 


Plants  as  Affected  by  Parasites.  153 

phosphoric  acid  is  indicated  by  scanty  crops  of  light  or 
shrunken  seed  on  plants  of  normal  size.  Lack  of  potash 
is  indicated  by  small  crops  of  inferior  fruit,  accompanied 
by  satisfactory  growth. 

268.  Crop    Rotation    Economizes    Plant    Food,  because 
some  crops  use  more  of  a,  given  food  constituent  than 
others.     The  alternating  of  crops  having  different  food 
requirements  tends  to  prevent  the  exhaustion  of  special 
food  substances. 

269.  A  Growing   Crop  Tends  to  Conserve   Fertility,  be- 
cause it  reduces  drainage  by  taking  up  water  from  the 
soil,  and  at  the  same  time,  appropriates  the  available  plant 
food,  thus  preventing  loss  of  the  latter  from  leaching. 

270.  Manures  are,  in  part,  the  Raw  Material  from  which 
the  cultivator  turns  out  valuable  products.    They  should, 
therefore,  be    most    carefully   preserved    and    applied. 
Leaching  of  the  manure  pile  by  undue  exposure  to  rain 
and  over-rapid  fermentation,  by  which  nitrogen  escapes 
as  ammonia  or  other  gaseous  nitrogen  compounds,  should 
be  stringently  avoided.   All  refuse  organic  matter  should, 
so  far  as  possible,  be  made  to  increase  the  always-too- 
small  stock  of  manure. 

SECTION  VII.     PLANTS  AS  AFFECTED  BY  PARASITES 

The  only  instance  of  a  beneficial  plant  parasite  (24) 
of  special  interest  to  the  cultivator,  is  the  micro- organ- 
isms in  the  roots  of  leguminous  plants,  which  we  have 
already  considered  (260).  Many  parasites  of  harmful 
insects  are  beneficial,  but  these  are  beyond  our  scope. 
We  need  therefore  to  treat  here  only  those  parasites  that 

are  directly  injurious  to  economic  plants. 
10 


154  Principles  of  Plant  Culture. 

271.  The  Injurious  Parasites  of  plants  are  Very  Numer- 
ous and  a  scientific  classification  of  them  is  beyond  the 
limits  of  this  work.     We  shall  only  endeavor  to  arrange 
the  different  parasites  into  groups  based  on  their  manner 
of  working  injury  and  the  methods  by  which  they  may 
be  controlled. 

With  reference  to  the  character  of  their  injury  and 
the  preventives  used,  as  well  as  in  their  natural  character- 
istics, plant  parasites  are  readily  separable  into  two  great 
classes,  viz.,  animal  and  vegetable  parasites.  These 
classes  will  be  considered  in  their  order. 

A  —  PLANTS  AS  AFFECTED  BY  ANIMAL  PARASITES 

a  — By  quadrupeds  and  birds.  The  four-footed  ani- 
mals that  injure  cultivated  crops  nearly  all  belong  to  the 
class  known  as  rodents,  which  includes  mice,  gophers, 
rabbits,  wood  chucks,  moles  etc.  These  may  usually  be 
controlled  by  trapping,  shooting,  or  poisoning,  or  by  pro- 
tecting the  plants. 

272.  Damage  from  Mice  to  orchard  and  nursery  trees 
is  very  common.     Mice  are  usually  most  troublesome  on 
sod  ground  covered  with  snow,  especially  beneath  snow 
banks,  hence  all  grass  should  be  removed  in  autumn 
from  the  immediate  vicinity  of  the  trees.     It  is  well  to 
ridge  the  soil  a  little,  directly  about  the  trees,  so  that  the 
mice  in  burrowing  beneath  the  snow  will  not  be  likely  to 
come  in  contact  with  the  stems.     Packing  the  snow  im- 
mediately about  the  trees  is  helpful  when  damage  is  dis- 
covered during  winter.     The  stems  of  orchard  trees  may 
also  be  wrapped  in  heavy  paper  or  inclosed  in  fine  wire 
netting.     If  tarred  paper  is  used,  it  should  be  promptly 
removed  in  spring,  or  it  may  injure  the  bark. 


Plants  as  Affected  ~by  Animal  Parasites.          155 

Stored  seeds  of  almost  all  kinds  must  be  carefully 
guarded  against  mice. 

273.  Gophers  are  often  troublesome  by  eating  planted 
seeds  and  by  burrowing  about  the  roots  of  young  orchard 
trees.    .They  may  be  poisoned  by  placing  corn,  soaked 
in  a  weak  solution  of  strychnin  in  water,  about  their 
holes. 

274.  Rabbits   are   especially  troublesome   to   nursery 
trees,  when  the  ground  is  covered  with  snow.     The  most 
satisfactory  protection  is  to  inclose  the  nursery  with  a 
fence  of  poultry  netting,  which  should  be  banked  up  a 
little  at  the  bottom  to  prevent  the  rabbits  from  passing 
under.     It  should  be  high  enough  to  reach  above  the 
surface  of  the  deepest  snow. 

Orchard  trees  may  be  protected  against  rabbits  by  in- 
closing the  trunks  with  the  devices  mentioned  under 
sun-scald  (186).  Smearing  the  stems  with  blood  has  also 
been  recommended. 

275.  Woodchucks   are   often   troublesome  to  growing 
crops,  but   as  they  are   seldom  numerous,  shooting   or 
trapping  generally  suffices  to  prevent  serious  damage. 
Moles  are  very  troublesome  in  some  localities  by  eating 
the  roots  of  plants.     They  may  be  largely  controlled  by 
the  use  of  mole- traps.     Pouring  a  little  carbon  bisulfid 
into  their  holes  is  also  generally  effectual. 

276.  Birds  are  often  troublesome  by  eating  unharvested 
fruits  and  seeds.     Inclosing  the  trees  or  plants  with  fish 
netting,  when  this  is  practicable,  is  perhaps  the  most 
satisfactory  preventive.     The  netting  is  not  expensive, 
and  the  same  piece  may  be  used  several  seasons. 

b  By  insects,  worms,  slugs  and  snails.  As  worms, 
slugs  and  snails  work  the  same  kind  of  injuries  as  some 


156  Principles  of  Plant  Culture. 

insects  and  are  controllable  by  the  same  methods,  we  do 
not  distinguish  between  them  in  the  following  paragraphs. 

277.  Many  Insects  are  Beneficial  by  destroying  harmful 
insects  or  by  promoting  pollination  (151).     We  should 
nob,  therefore,  wage    indiscriminate    warfare    upon    all 
insects. 

278.  Methods  of  Preventing  Insect  Ravages  to  plants 
are  various,  as  inclosing  the  plants,  trapping,  repelling 
or  removing  the  insects,  destroying  them  by  means  of 
insecticides,  or  preventing  reproduction  by  destroying  the 
eggs.     The  important  question  in  the  case  of  any  injur- 
ious  insect  is  by  which  one  of  these   methods  it  may 
be  most  effectually  and  cheaply  controlled. 

279.  Inclosing  the  Plants  is  practicable  in  a  few  cases, 
as  with  the   striped   cucumber   beetle.*     The  hills  in 

which  cucumbers,  mel- 
ons, squashes  etc.,  are 
planted,  may  be  covered 

FIG.  67.    Screen-covered  frame  for  pro-  with     a     frame     having 
tecting  hills  of  the  melon  and  cucumber.     fine.meshed    wire_     or 

cotton  netting  tacked  over  the  top,  which  prevents  the 
beetles  from  gaining  access  to  the  plants  (Fig.  67). 

280.  Trapping  the  Insects  is  practicable  in  a  few  cases, 
as  with  cutworms,  which  often  conceal  themselves  during 
the  day  beneath  objects  on  the  ground.     They  will  fre- 
quently be  found  in  numbers  beneath  handfuls  of  green 
clover  or  other  herbage  placed  on  the  ground  near  the 
plants  which  it  is  desired  to  protect.     By  poisoning  the 
herbage   (284),  some  of  the  cutworms  may  be  killed, 
but  many  are  likely  to  escape  unless  destroyed  by  other 
means. 


*  Diabrotica  vittata. 


Plants  as  Affected  by  Animal  Parasites.          157 

281.  Repelling  Insects  by  means  of  offensive  odors  is 
partially  effectual  in  some  cases,  as  with  the  squash- vine 
borer.*     Corncobs  or  other  objects,  dipped  in  coal  tar 
and  placed  among  the  plants,  repel  many  of  the  moths 
that  produce  the  borers. 

282.  Hand  Picking,  i.  e.,  removing  the  insects  from  the 
plants  by  hand,  is  the  most  satisfactory  method  for  de- 
stroying certain  insects,  as  the  tobacco-  or  tomato  worm,f 
and  other  large   caterpillars,  and  the  rose- beetle.  J     A 
vessel  of  water  with  a  little  kerosene  on  the  surface,  in 
which  to  throw  the  insects  as  they  are  gathered,  is  a  con- 
venient way  of  destroying  them.     In  some  cases,  the  in- 
sects can  be  shaken  or  knocked  from  the  plant  directly 
into  the  vessel.     This  method  is  often  employed  in  de- 
stroying the  potato  beetle.  §     Digging  out  cutworms  and 
white  grubs  1 1  from  about  corn  and  strawberry  plants, 
and  cutting  out  borers  from  trees  and  squash  vines  are 
often  the  most  effectual  methods  for  destroying  these 
insects. 

283.  Destroying  Insects  by  Poisons  or  Caustics  is  the 
method  most  generally  available.     The  material  used  is 
called  an  insecticide  (in-sect'-i-cide),  and  if  satisfactory, 
must  be  destructive  to  the  insects  without  injuring  the 
plant  to  which  it  is  applied,  or  rendering  the  plant  or  its 
products  unfit  for  food.     The  insecticides  in  most  gen- 
eral use  are  certain  compounds  of  arsenic  (Paris  green, 
London  purple,  white  arsenic),  hellebore  and  pyrethrum 
powders,  tobacco,  kerosene   and  various  compounds  of 
soda  and  potash.     With  the  exception  of  kerosene  and 

*  Melittia  ceto.      f  Phlegethontius  celeus.      J  Macrodactylus  subspinosus. 
\  Doryphora  decenilineata.        []  Lachnosterna. 


158  Principles  of  Plant  Culture. 

the  soda  and  potash  compounds,  all  these  may  be  used 
either  as  a  dry  powder  or  with  water. 

284.  The  Arsenic  Compounds  are  effectual  as  insect  de- 
stroyers, even  when  largely  diluted.     AYhen  applied  in 
water,  however,  they  are  liable  to  injure  foliage  in  pro- 
portion to  the  amount  of  soluble  arsenic  they  contain. 
When  insoluble  in  water,  they  require  stirring  to  keep 
them  in  suspension. 

285.  Paris  Green  (arsenite  of  copper),  when  pure,  is  a 
nearly  insoluble  compound  and  may  be  safely  used  upon 
the  foliage  of  most  plants,  diluted  at  the   rate  of  one 
.pound  to  two  hundred  gallons  of  water.     For  the  peach 
and  nectarine  it  should  be  diluted  one-half  more.    Pure 
Paris  green  dissolves  without  sediment  in  ammonia  water. 

286.  White  Arsenic  (arsenious  acid)  is  slightly  soluble 
in  water,  and  hence  is  dangerous  to  foliage  unless  used 
with  care.     If  applied  immediately  after  its  addition  to 
the  water,  it  may  be  safely  used  upon  the  foliage  of  the 
apple,  plum  and  cherry  at  the  rate  of  one  pound  to  fifty 
gallons,  but  constant  stirring  is  required  to  keep  it  in 
suspension. 

287.  London  Purple  (arsenite  of  lime,  with  certain  im- 
purities) often  contains  soluble  arsenic,  and  like  white 
arsenic,  must  be  used  with  caution.     It  may  be  safely 
applied  to  many  plants  at  the  rate  of  one  pound  to  two 
hundred  gallons  of  water,  if  put  on  immediately  after  its 
addition  to  the  liquid,  but  for  the  peach  it  should  receive 
greater  dilution.     London  purple  is  considerably  cheaper 
than  Paris  green. 

The  addition  of  fresh  milk  of  lime  to  water,  to  which 
white  arsenic  or  London  purple  has  been  added,  largely 
prevents  their  tendency  to  injure  foliage. 


Plants  as  Affected  by  Animal  Parasites.          159 

Both  Paris  green  and  London  purple,  when  perfectly 
mixed  with  150  parts,  by  weight,  of  land  plaster,  or  an 
equal  bulk  of  any  other  cheap,  harmless  powder,  are 
satisfactory  for  destroying  the  potato  beetle  and  many 
other  leaf-eating  insects  (307). 

288.  Compounds   of  Arsenic   are    Deadly  Poisons   and 
should  always  be  handled  with  the  greatest  care. 

289.  Hellebore  (hel'-le-bore)  Powder,  i.  e.,  the  ground 
root  of  white  hellebore,*  is  a  far  less  virulent  poison 
than  the  arsenic  compounds.     It  is  therefore  useful  in 
destroying  a  class  of  insects   against  which   a   deadly 
poison  cannot  wisely  be  used,  as  the  imported  currant 
worm,  f  and  the  cabbage  caterpillar.  J 

Hellebore  powder  when  used  dry,  may  be  diluted  with 
once  or  Jbwice  its  bulk  of  flour,  which  causes  it  to  adhere 
better  to  the  foliage  than  if  used  alone.  When  applied 
with  water,  a  heaping  teaspoonful  or  more  may  be  added 
to  three  gallons.  The  dry  powder  is  very  light  and 
should  only  be  used  in  a  still  atmosphere. 

A  decoction  made  by  boiling  the  root  of  white  helle- 
bore in  water  is  said  to  possess  insecticide  properties 
similar  to  those  of  the  powder. 

290.  Pyrethrum  (py- re' -thrum)  Powder,  (Persian  in- 
sect powder,  Dalmatian  insect  powder,  Buhach)  is  the 
pulverized  flowers  of  certain  species  of  Pyrethrum.  § 

Pyrethrum  powder  is  not  poisonous  to  the  higher  ani- 
mals, but  the  oil  that  pervades  it  is  destructive  to  many 

*  Veratrum  album.       f  Nematus  ribesii.       J  Pierls  rapce. 

g  "Persian  insect  powder"  is  made  from  the  flowers  of  Pyrethrum 
roseum  and  P.  carneum.;  "Dalmatian  insect  powder"  and  "Buhach" 
are  made  from  those  of  P.  cineraicefolium.  "  Buhach  "  is  the  trade  name 
of  a  pure  product  prepared  in  California. 


160  Principles  of  Plant  Culture. 

insects.  As  the  oil  is  extremely  volatile,  pyrethrum  is 
better  adapted  for  use  under  glass  or  with  plants  other- 
wise inclosed.  It  is  not  injurious  to  foliage  or  flowers. 
Fresh  and  pure  pyrethrum  powder  may  be  dilated  half 
or  more  in  bulk  with  any  other  light,  cheap,  harmless 
powder,  but  the  mixture  should  stand  a  day  or  two  before 
use,  to  enable  the  diluent  to  absorb  the  oil.  The  powder 
may  be  used  with  water  at  the  rate  of  half  a  pound  to 
three  gallons. 

The  pyrethrum  plant  is  comparatively  hardy  and  has 
been  successfully  grown  in  northern  United  States.  It 
is  said  that  a  decoction  of  the  unopened  flowers  posses- 
ses the  insecticide  properties  of  the  commercial  product. 

291.  Hellebore  and  Pyrethrum  Powders  should  be  Kept 
in  Close  Vessels,  since   their   poisonous   properties   are 
volatile.     In  purchasing,  only  fresh  samples  should  be 
accepted.     If  fresh  and  pure,  these  powders  produce  a 
tingling  sensation  when  applied  to  the  nostrils. 

292.  Tobacco    Smoke   is   much    used    for   destroying 
"lice"  or  " green  fly"  (aphidre)  on  plants  under  glass. 
For  this  purpose,  the  partially-dry  stems  or  leaves  are 
burned  upon  pans  or  bricks,   or   in   small    sheet-iron 
stoves.     Many  delicate  flowers  are,  however,  injured  by 
tobacco  smoke. 

Stems  or  leaves  of  tobacco,  strewn  abundantly  beneath 
greenhouse  benches,  tend  to  prevent  the  multiplication 
of  aphida?. 

Several  semifluid  extracts  of  tobacco  are  sold  which 
may  be  evaporated  in  the  greenhouse  over  an  oil  stove, 
or  preferably  by  steam  under  pressure.  Some  of  these 
are  very  efficient  for  destroying  insects  and  do  not  injure 
flowers. 


Plants  as  Affected  by  Animal  Parasites.          161 

293.  A  Strong  Decoction  of  Tobacco  is  often  used  for 
destroying   aphidne  on  plants  in  rooms  where  tobacco 
smoke  would  be  objectionable.    The  plants  are  immersed 
in,  or  washed  with  the  decoction.     The  same  is  often 
effectually  used  on  young  plants  of  cabbage,  cauliflower 
and   turnip,  to   prevent  their   destruction  by  the   flea 
beetle.* 

294.  Kerosene  is  a  very  useful  insecticide  for  a  class 
of  insects  not  readily  destroyed  by  other  means  (316). 
It  has  generally  been  used  as  an  emulsion  made  with 
soap  and  water,  for  which  the  following  formulas  are 
good. 

a  —  Dissolve  one  quart  of  soft  soap,  or  one-fourth 
pound  of  good  hard  soap,  in  two  quarts  of  boiling  water; 
remove  from  the  fire,  and  pour  into  a  tin  can  containing 
one  pint  of  kerosene.  Agitate  violently  in  the  can  for 
three  minutes.  For  use,  dilute  with  an  equal  quantity 
of  water;  or 

b  —  Dissolve  one-half  pound  of  hard  soap  in  one  gal- 
lon of  boiling  soft  water;  add  at  once  two  gallons  of  kero- 
sene, and  churn  or  otherwise  violently  agitate  for  five  or 
ten  minutes.  For  use,  dilute  with  15  parts  of  soft  water. 

Kerosene  may  also  be  applied  in  intimate  mixture  with 
water,  secured  by  pumping  both  liquids  at  once  through 
a  good  spraying  nozzle  (Fig.  70).  About  ten  per  cent 
of  kerosene  should  be  used  for  most  plants. 

295.  Caustic  Potash  in  solution  is  useful  for  destroying 
certain  scale  insects,  as  the  oyster-shell  bark-louse,  f  for 
which  solutions  of  one-fourth  pound  to  the  gallon  of 
water  may  be  applied  during  winter. 

*  Phyllotreta  vittata.  f  Mytilaspis  pomorum. 


162  Principles  of  Plant  Culture. 

296.  Resin  (or  rosin)  Washes  are  valued  for  destroy- 
ing various  scale  insects  in  southern  and  western  United 
States.     They  are  adapted  with  modifications  to  both 
dormant   and   growing   trees.     The   resin  is  sometimes 
saponified  with   caustic   soda  and  simply  diluted  with 
water;  fish  oil  or  petroleum  may  also  be  added.     The 
following  and  other  formulas  are  in  use: 

a  —  Dissolve  one  pound  of  caustic  soda  in  one  gallon 
of  water  in  a  covered  iron  kettle.  Pour  out  half  of  the 
solution,  and  to  the  remainder  add  8  pounds  of  resin  and 
boil  until  dissolved.  Then  pour  in  very  slowly  the  rest 
of  the  caustic  soda  solution  and  boil  the  whole,  stirring 
it  constantly,  until  it  will  unite  with  water,  forming  a 
liquid  resembling  milk.  Dilute  to  22  gallons  for  use. 
This  mixture  may  be  applied  during  the  growing  sea- 
son; or 

b  —  Place  30  pounds  of  resin,  9  pounds  of  70  per  cent 
caustic  soda  and  4^  pints  of  fish  oil,  in  a  closed  iron 
kettle  and  cover  with  five  or  six  inches  of  water.  Boil 
until  the  liquid  has  a  dark-brown  color,  after  which 
slowly  add  water  until  the  whole  makes  100  gallons;  or 
dilute  a  part  of  the  liquid  at  this  rate,  keeping  the  re- 
mainder as  a  stock  solution.  This  is  for  use  in  the  dor- 
mant season.  For  the  growing  season,  similar,  but  more 
dilute  solutions  are  used. 

297.  Hydrocyanic  Gas.     Another  method  of  destroying 
scale  insects  used  in  California  and  the  Southern  States 
is  to  treat  the  tree,  previously  inclosed  in  an  oil  cloth 
tent,  with  hydrocyanic  gas.     One  ounce  of  cyanid  of 
potassium  and  one  measured  ounce  of  sulfuric  acid  are 
placed  in  an  earthern  or  leaden  jar   containing   three 


Plants  as  Affected  by  Animal  Parasites.          163 

fluid  ounces  of  water.  The  jar  is  covered  with  burlaps 
to  prevent  the  rapid  escape  of  the  gas.  The  tent  is  left 
over  the  tree  fifteen  minutes  to  one  hour.  It  is  advisable 
to  apply  this  treatment  during  the  dormant  season  and 
in  a  cool  period. 

298.  Fir-Tree  Oil  is  considerably  used  in  greenhouses 
and  conservatories  for  destroying  scale  insects  and  the 
mealy  bug.*     It  is  mixed  with  warm  soft  water  at  the 
rate  of  a  tablespoonful  of  oil  to  a  pint,  and  applied  with 
a  syringe;  or  the  plants  are  dipped  into  the  mixture. 

299.  Hot  Water  may  also  be  used  for  destroying  the 
above-named  insects  (298)  and  plant  lice  (aphidre).    In- 
fested pot-plants  are  inverted  and  immersed  five  or  six 
seconds  in  a  vessel  containing  water  at  120°  F.     This 
treatment  must  be  used  with  caution. 

300.  Insect  Attacks  Sometimes  Become  Formidable  from 
the  vast  number  of  the  individuals.     The  chinch-bug,  f 
the  army-worm  J  and  various  species  of  locusts  or  grass- 
hoppers sometimes  devastate  large   tracts  of  country. 
For  the  destruction  of  these  insects,  special  means  must 
be  employed. 

301.  The  Chinch-Bug  may  be  controlled  in  a  measure, 
by  burning  over  all  grass  land  in  early  spring,  in  seasons 
when  attacks  are  expected.     The  bugs  may  be  kept  out 
of  corn  fields  by  plowing  a  furrow  away  from  the  corn, 
on  the  side  from  which  the  attack  is  looked  for,  and 
strewing  stalks  of  fresh  corn  in  this.     As  the  insects 
congregate  on  the  corn  in  the  furrow,  they  should  be  de- 
stroyed with  kerosene  (294).     Persistent  and  thorough 
work  is  essential  to  success. 


*  Dactylopius.       f  Blissus  leucopterus.        %  Leucania  unipuncta. 


164 


Principles  of  Plant  Culture. 


302.  The  Army-Worm  may  often  be  prevented  from  mi- 
gration by  plowing  a  deep  furrow,  as  above  directed, 
and  making  the  side  toward  the  endangered  crop  verti- 
cal, with  a  spade  or  shovel.     The  insects  will  congregate 
in  the  furrow  where  they  may  be  destroyed  by  dragging 
a  log  over  them. 

303.  Grasshoppers  and  Locusts  may  be  destroyed,  be- 
fore they  have  attained  their  wings,  by  drawing  over  the 
infested  ground,  a  "  hopper-doser "  which  consists  of  a 
shallow,  sheet-iron   pan,  with   a  vertical,  cloth-covered 
back.     The  pan  contains  a  little  kerosene,  and  the  cloth 
back  is  kept  saturated  with  the  same  liquid.    The  insects 
jump  into  the  pan  or  against  the  cloth  back,  thus  becom- 
ing wet  with  the  kerosene,  and  soon  perish.     Grasshop- 
pers may  also  be  poisoned  by  distributing  bran  mixed 

into  a  mash  with  water  containing  ar- 
senic in  solution.     Plowing  grass  land 
containing   the    eggs   of    grasshoppers 
tends  to  prevent  an  attack. 
304.  Apparatus  for  Ap- 
B  plying  insecticides.     Pow- 
ders are   readily  applied 
upon  low-growing  plants, 
as  the   potato,  cabbage 
etc.,  by  means  of  a  sifting 
Abox   consisting  of  a  pail 
with  a  perforated  bottom, 
a  rigid  handle  and  a  tight- 
fitting   cover  (Fig.  68). 
FIG.  68.    sifting  box  for  applying  For  small  plants,  as  young 
powders.  potato  tops,  the  tin  disc  A 

which  has  a  circular  hole  in  the  center,  is  laid  inside  on 
the  bottom  of  the  box,  and  held  in  place  by  small  lugs 


Plants  as  Affected  by  Animal  Parasites. 


165 


soldered  to  the  wall  as  shown.     When  it  is  desired  to 
spread  the  powder  more,  the  disc  B  is  used. 

For  taller  plants,  a  powder  bellows  is  desirable. 

Liquids  are  best  distributed  with 
a  force  pump,  fitted  with  a  hose  of 
a  length  suitable  to  the  height  of 


FIG.  tin.  FIG.  70. 

Fig.  69.  A  convenient  and  serviceable  spray  pump,  using  a  common 
pail  for  a  reservoir,  to  which  it  is  attached  by  the  device  shown  at  the  left. 

Fig.  70.  A  similar  pump  with  attachment  by  which  kerosene  and 
water  may  be  sprayed  together  (294).  Both  are  made  by  the  Deming  Co.T 
Salem,  Ohio. 

the  tree  or  plant,  and  with  an  atomizing  nozzle  (Figs.  69, 
70,  71).  For  tall  trees,  the  hose  nozzle  may  be  elevated 
by  attaching  it  to  the  end  of  a  light  pole.  In  orchard 
spraying,  the  pump  is  often  used  on  a  wagon,  and  the  man 
holding  the  hose  sometimes  stands  on  a  high  platform. 
A  spray  pump  used  on  a  large  reservoir,  needs  an  agitator 
to  prevent  the  heavier  part  of  the  spraying  mixture  from 
settling. 

Excellent  bellows  and  force  pumps,  designed  expressly 
for  applying  insecticides,  are  now  manufactured. 

305.  The  Use  of  Insecticides.  In  treating  any  given 
insect,  the  most  important  question  to  decide,  is  the  man- 


166 


Principles  of  Plant  Culture. 


ner  in  which  it  works  its  injury,  as  upon  this  will  depend 
the  preventive  measures  to  be  used. 

306.  Injurious  Insects  are  referable  to  Two  Classes,  viz., 
eating  insects,  i.  e.,  those  feeding  directly  upon  the  plant 
tissues,  as  the  potato  beetle,  the  apple-tree 
borers,*  the  plum  curculio;  f  and  the  suck- 
ing insects,  i.  e.,  those  feeding  only  upon  the 
juices  of  the  plant,  as  plant  lice,  the  squash- 
bug,  %  and  the  oyster-shell  bark-louse.  § 

307.  The  Eating    Insects  may  be   subdi- 
vided into  leaf-eaters,  those  that  devour  the 
foliage;   root-eaters,  those   that   devour  the 
roots  5   and  bur  rowers,  those  that  har- 
bor within  some    part  of  the 
plant  by  eating  a  passage  for 
their  bodies. 

308.  The  Leaf-Eaters  include 
numerous  species.  They  are 
readily  recognized  by  the  fact 
that  the  leaves,  on  which  they 
a  feed,  disappear 

more  or  less  rap- 
idly. They  may 
generally  be  d e- 
stroyed  by  apply- 
ing a  poison  to  the 
foliage,  for  which 
purpose  the  arsen- 

PiG.71.    Steam  spraying  outfit,  manufactured  leal  Compounds  are 
by  the  Shipman  Engine  Co.,  Rochester,  N.  Y.        well  adapted  (284). 

In  cases  where  the  use  of  a  deadly  poison  is  unsafe,  hel- 
lebore (289)  or  pyrethrum  (290)  may  be  substituted. 

*  The  round-headed  apple-tree  borer,  Saperda  Candida;  the  flat-headed 
apple-tree  borer,  Chrysobothris  femorata.  f  Conotrachelus  nenuphar. 

I  Anasa  tristis.          $  Mytilaspis  pomorum. 


Plants  as  Affected  by  Animal  Parasites. 


167 


309.  The  Root-Eaters  include  fewer  species  than  the 
leaf -eaters  and  are  usually  more  difficult  to  control. 

Carbon  bisulfid,  injected  into  the  soil  about  the  roots 
of  cabbage  and  cauliflower  plants,  with  an  instrument 
devised  for  the  purpose  (Fig.  72),  has  been  successfully 
used  to  destroy  the  cabbage  maggot,*  and  may  be  found 
useful  in  other  cases.  Attacks  of  this  insect  have  also 
been  successfully  prevented  by  surrounding 
the  stem  of  the  young  plant  with  small 
cards  of  thin  tarred  paper.  One  of  these 
cards,  the  tool  used  for  cutting  them,  and 
the  manner  of  using  the  tool  are  shown  in 
Figs.  72,  73  and  74. 

310.  Burrowers,  as  the  term  is  here  used, 
include  not  only  the  so-called  borers  that 
burrow  within  the  stems  and  roots 
^  of  plants,  and  the  leaf -miners,  that 
live  between  the  surface  of  leaves, 
but  also  the  insects  that  pass  their 
larval  stage  within  fruits.     Insects 

FIG.  72.    Tool  for  injecting 
poisonous  liquids  about  the   OI   this   ClaSS   are    difficult   to    CO11- 


rootsof  plants.  ^roi?  since  they  are  mostly  beyond 

the  reach  of  insecticides. 

311.  Borers  that  infest  the  trunks  and  main  branches 
of  trees,  may  often  be  kept  out  by  applying  strong  alka- 
line washes  to  these  parts.  Soft  soap,  reduced  to  the 
consistency  of  thick  paste  by  a  strong  solution  of  wash- 
ing soda,  applied  to  the  trunk  or  branches,  forms  a  rather 
tenacious  coating  which  repels  the  female  insect.  Paint- 
ing the  trunks  of  small  apple  trees  a  short  distance  above 
and  below  the  surface  of  the  ground  with  common  paint 

*  PJiorbia  brassicce. 


168 


Principles  of  Plant  Culture. 


or  pine  tar,  is  said  to  prevent  the  entrance  of  the  round- 
headed  borer  (306).  Protecting  the  trunk  with  straw  or 
lath,  as  recommended  to  prevent  sun-scald  (186),  may 
tend  to  keep  out  these  insects.  Borers  in  the  trunk  can 
often  be  destroyed  by  probing  their  holes  with  a  flexible 
twig. 

3f2.  Leaf-Miners  often  infest  spinach  and  beets  grown 
for  greens,  rendering  the  leaves  unfit  for  use.  For  these 
insects  we  can  offer  no  preventive  measures  of 
established  value.  The  application  to  the 
young  foliage  of  powerful  odorants,  as  coal-tar 
water  or  a  solution  of  carbolic  acid,  may  prove 
beneficial. 

313.  The    Codling-Moth,*   which   causes  so- 
called  ' i  wormy ' '  apples  and  pears,  is  controlled 
by  spraying  the  trees  at  the  time  of  egg  de- 
posit, with  water  containing  Paris  green  (285). 
The   first  spraying  should  be 
given   as  soon   as  the   petals 
(143)  fall,  to  be  followed  by  a 
second   six  to 
ten  day  slater. 
If  much   rain 
falls  at  this 
season,  the 
sprayings  may 
need  frequent 
repetition.     A 


FIG.  74. 


Fig.  73.  Card  of  tarred  paper,  for  placing  about  the 
stems  of  young  cabbage  and  cauliflower  plants.  Re- 
duced one-half. 

Fig.  74.    Tool  for  cutting  the  cards. 

Fig.  75.  Manner  of  using  the  tool.  The  dotted  lines 
drop  of  poison-  show  the  position  of  the  edge  of  the  tool  on  the  paper. 

ed  water  should  be  lodged  in  the  calyx  (142)  of  every 
fruit,  and  as  this  evaporates,  the  poison  deposited  on  the 


Carpocapsa  pomonella. 


Plants  as  Affected  by  Animal  Parasites.          169 

skin  kills  the  newly-hatched  insect  as  it  eats  its  way 
inward. 

A  band  of  cloth  or  paper,  placed  about  the  trunk  of 
fruiting  apple  or  pear  trees  forms  a  convenient  retreat 
for  larvae  of  the  codling- moth,  in  which  to  pupate.  They 
may  then  be  readily  destroyed  by  removing  the  band. 
The  bands  should  be  a  few  inches  wide,  and  should  be 
put  on  before  midsummer.  They  should  be  taken  off 
once  in  ten  to  fourteen  days,  until  the  fruit  is  harvested, 
and  all  cocoons  beneath  them  should  be  crushed. 

314.  The  Plum  Curculio  (306)  that  so  often  stings  young 
plums,  causing  them  to  drop  before  maturity,  is  controlled 
by  jarring  the  beetles,  that  deposit  their  eggs  in  the 
young  fruit,  upon  sheet- covered  frames  on  cool,  still 
mornings  while  their  muscles  are  stiff  (Fig.  76).  The 
jarring  should  begin  almost  as  soon  as  the  petals  (143) 
fall,  and  should  be  repeated  every  still  morning  as  long 
as  any  beetles  are  found.  The  work  must  be  done  in 
the  early  morning.  Any  light  wood  frame,  covered  with 
cloth  may  be  used  as  a  substitute  for  the  more  convenient 
device  shown  in  the  figure.  Where  the  substitute  is 

used,  the  beetles 
must  be  looked  for 
on  the  sheet  and 
destroyed  as  found. 

315.  The  Prompt  De- 
struction of  Infested 

FIG.  76.    Curculio  catcher.    It  is  wheeled  be-  fruits  materially  aids 
neath  the  branches  of  the  tree,  and  the  latter  .  .  J 
are  struck  with  a  light,  cloth-covered  mallet,  in  keeping  the  fruit- 
which  jars  the  beetles  upon  the  sheet-covered  blirrowin0*  insects  in 
frame,  from  which  they  roll  into  the  box  be- 
neath.    For    small  trees,  the  trunk  slips  in  Subjection.         H  O  g  S 
through  the  slot  at  the  left.  and    sheep  ill  the  Or- 
11 


170  Principles  of  Plant  Culture. 

chard  are  most  valuable  assistants  in  this  work.  The 
apple- maggot*  is  more  effectually  controlled  in  this  man- 
ner than  by  any  other  known  method. 

316.  Sucking  Insects  include  many  species.     They  feed 
on  the  juices  of  the  plant  which  they  infest,  and  do  not 
directly  devour  its  tissues,  as  do  the  eating  insects;  but 
they  reduce  its  vitality  by  their  continual  drain  upon 
the  reserve  food.     The  so-called  scale  insects  belong  to 
this  class.     These  are  especially  difficult  to  destroy,  since 
they  are  dormant  the  greater  part  of  the  year,  and  in 
this  condition  are  protected  by  their  comparatively  re- 
sistant scales. 

Sucking  insects  are  not  susceptible  to  poisonous  insect- 
icides, hence  we  must  resort  to  materials  that  clog  their 
breathing  pores,  as  kerosene  (294),  that  dissolve  their 
eggs  and  scales,  as  potash  solutions  or  that  form  an  air- 
tight coating  over  them,  as  the  resin  washes  (295).  f 

317.  The  Life  Histories  of  Injurious  Insects,  which  can 
not  here  be  taken  up,  may  profitably  be  studied  by  the 
plant  grower.    A  standard  work  on  economic  entomology 
will  furnish  the  needed  information. 

B  —  PLANTS  AS  AFFECTED  BY  VEGETABLE  PARASITES. 

318.  Many  of  the  most  serious  enemies  of  cultivated 
plants  belong  to  this  class.  As  a  rule,  vegetable  parasites 
contain  no  chlorophyll,  and  hence  are  incapable  of  form- 
ing their  own  food.     While  most  of  them  belong  to  the 
lower  orders  of  plants,  a  few  species  are  highly  developed 
and  produce  true  flowers  and  seeds. 

*  Trypeta  pomonella. 

f  The  cottony  cushion  scale,  Icerya  purchasi,  which  was  very  destruc- 
tive to  the  orange  in  California,  has  been  nearly  suppressed  by  the  intro- 
duction of  an  Australian  parasite,  the  Vedalia  cardinalis. 


Plants  as  Affected  by  Fungous  Parasites.         171 

a  —  By  Flowering  or  phanerogamic  (phan'-er-o-ga'- 
mic)  parasites. 

Of  these,  the  only  ones  sufficiently  common  or  injurious 
to  need  mention  are  the  broom  rapes  and  the  dodders. 

319.  The  Broom   Rape  of  Hemp  and  Tobacco,*  is  the 
most  injurious  species  of  this  class.   The  seeds  germinate 
in  the  soil,  and  the  young  plants  attach  themselves  to  the 
roots  of  their  host  which  they  enfeeble  by  robbing  them 
of  nourishment.     In  the  case  of  hemp,  the  parasite  also 
injures  the  quality  of  the  fibre. 

Preventives.  The  seeds  of  hemp  or  tobacco  should  not 
be  taken  from  a  crop  infested  with  broom  rape.  Infested 
fields  should  be  planted  for  several  years  to  some  crop 
not  attacked  by  broom  rape,  as  potatoes,  Indian  corn, 
beans,  grains  or  grasses.  In  infested  crops,  the  broom 
rape  should  not  be  permitted  to  mature  its  seeds. 

320.  The  Dodders  of  Clover  and  Flax,f  are  the  most 
injurious  of  their  class.     The  young  plant  attaches  itself 
to  the  stem  of  its  host,  about  which  it  twines,  robbing  it  of 
nourishment  by  means  of  small  suckers. 

Preventives.  The  seeds  of  dodder  are  somewhat  smaller 
than  those  of  clover  or  flax,  and  hence  may  be  separated 
from  the  latter  by  sifting.  Badly  infested  ground  should 
be  devoted  for  two  to  four  years  to  a  crop  not  attacked 
by  the  dodder. 

b      Plants  as  affected  by  fungous  parasites. 

321.  The  Fungi  constitute  an  extensive  class  of  plants 
that  derive  their  nourishment  wholly  from  organic  matter. 
Many  of  them  are  injurious  to  cultivated  plants.   Unlike 
the  harmful  insects,  most  of  which  work  their  ravages 

*  Philipcea  ramona.          f  Cuscuta  trifolia,  C.  Epilinum. 


172  Principles  of  Plant  Culture. 

within  full  view,  the  fungi  are  in  many  cases  discernible 
only  with  the  microscope,  and  reveal  their  presence  only 
by  the  death  or  injury  of  their  host.  The  fungous  para- 
sites are  very  numerous  and  exhibit  great  diversity  of 
structure  and  habit.  Some  of  them  live  only  upon 
enfeebled  plants,  while  others  attack  healthy  ones.  Some, 
as  the  pea  mildew,  grow  upon  the  surface  of  their  host, 
drawing  their  nourishment  through  the  epidermis;  others, 
like  the  peach  curl  and  oat  smut,  grow  within  the  tissues 
of  the  plant  upon  which  they  feed.  All  of  the  latter 
class  send  their  fruiting  parts  to  the  surface  of  the  host 
plants  to  disseminate  their  spores  in  the  open  air. 

The  fungi  multiply  from  extremely  minute  spores  (53) 
that  are  produced  in  immense  numbers,  and  when  mature, 
are  very  readily  blown  about  by  wind.  Many  of  them 
also  multiply  from  thread-like  organs  called  hyphce 
(hy'-phse),  something  in  the  same  manner  as  Canada 
thistles  multiply  from  their  roots. 

322.  Methods  of  Controlling  Fungi  are  of  three  classes  : 
a  —  Eemoving  and  destroying  the  affected  parts; 

b  —  Preventing  the  germination  of  the  spores; 
c  —  Destroying  the  fungus   itself  by  applying  some 
destructive  material  (a  fungicide  (fun'-gi-cide.)). 

323.  Destruction   of  the   Affected    Parts   is  the   most 
effectual  preventive  known  in  cases  where  the  fungous 
disease  attacks  a  portion  of  the  plant  whence  it  spreads 
to  the  remaining  parts,  as  in  the  black  knot  of  the  plum,* 
the  blight  of  the  pear,  apple  and  quince,  f  the  red  rust  of 
the  raspberry  and  blackberry,];  and  the  corn  smut. § 

*  Plowrightia  morbosa.       f  Microccocus  amylovorus. 
J  Cfeoma  luminatum.  \  Ustilago  Maydis. 


Plants  as  Affected  by  Fungous  Parasites.          173 

The  affected  part  should  be  removed  as  soon  as  dis- 
covered and  burned  at  once,  to  destroy  any  spores  of  the 
fungus  it  may  contain  or  which  might  mature  later.  It 
is  generally  important  to  cut  the  diseased  branch  some 
distance  below  the  point  of  visible  infection,  as  in  many 
cases  the  mycelia  of  the  fungus  extend  farther  than 
external  appearances  indicate. 

324.  Preventing  Spore  Germination  is  the  only  known 
method  by  which  we  can  combat  the  fungi  developing 
within  the  host  plant  (endophytic  (en  do-phyt'-ic)  fungi). 

In  fungi  that  develop  from  spores  planted  with  the 
seed,  as  the  smuts  of  the  small  grains,  spore  germination 
may  be  prevented  by  treating  the  seed  with  a  solution  of 
certain  chemicals  or  with  hot  water.  Of  the  former, 
sulfate  of  copper  (copper  sulfate,  blue  vitriol,  bluestone) 
has  been  most  used,  and  unquestionably  destroys  the 
spores  of  the  smuts,  but  it  has  generally  been  found  to 
injure  more  or  less  the  germination  of  the  seed. 

325.  The    Hot-Water   Treatment   has   proven   fully  as 
successful  in  preventing  smut  as  the  preceding  method, 
without  injuring  the  seed.     This  treatment  consists  in 
immersing  the  seed  for  ten  minutes  in  water  at  a  tem- 
perature of  about  135°  F.     For  treating  a  quantity  of 
seed,  some  special  provisions  are  necessary,  as  it  is  some- 
what difficult  to  bring  every  seed  in  contact  with  the 
water  at  the  proper  temperature.     Provide  two  large 
vessels,  as  two  kettles  over  a  fire,  or  two  boilers  over  a 
cook  stove  —  one  to  contain*  warm  water  (110-120°  F. ), 
the  other  to  contain  hot  water  (132-135°  F.).     Place  a 
reliable  thermometer  in  the  hot- water  vessel   that  the 
temperature  may  be  watched.      The  warm  water  is  used 


174  Principles  of  Plant  Culture. 

to  warm  the  seed,  before  dipping  it  in  the  hot  water  • 
otherwise  it  is  difficult  to  maintain  the  temperature  of 
the  latter.  The  seed  is  placed  in  a  covered  basket, 
preferably  of  wire  cloth,  in  quantity  not  exceeding  one- 
eighth  of  the  volume  of  the  water  ;  the  basket  should  be 
but  partially  filled.  Immerse  the  basket  several  times 
in  the  warm  water,  a  moment  at  a  time,  giving  it  a 
rotary  motion  in  order  to  bring  every  seed  in  contact 
with  the  water.  Then  plunge  it  into  the  hot  water  and 
repeat  the  immersions  as  before,  carefully  watching  the 
thermometer  in  the  meantime.  Should  the  temperature 
fall  below  132°,  add  water  of  a  higher  temperature  ;  and 
if  it  rises  above  135°,  add  cold  water.  After  the  seed 
has  been  in  the  hot  water  ten  minutes,  remove  the  basket 
and  plunge  it  into  cold  water,  then  spread  the  seed  out 
to  dry.  The  drying  need  not  be  thorough  unless  the 
seed  is  to  be  stored  for  a  time. 

326.  Fungi  that  Develop  from  Spores  Surviving  the  Winter 
In  or  Upon  the  Soil,  as  the  onion  *  smut,  cannot  be  pre- 
vented by  disinfecting  the  seed.     For  this  disease  a  mix- 
ture of  flowers  of  sulfur  and  air- slacked  lime,  sown  with 
the  seed,  has  proved  beneficial  by  preventing  infection 
of  the  young  plant. 

327.  Fungi   the   Spores  of  which   Survive  the  Winter 
Within  their  Dead-Host  Plants,  as  in  the  club-root  of  the 
cabbage  f  and  turnip,  and  the  onion  mil  dew,  J  may  be 
held  in  check  to  some  extent  by  burning  the  fungus- 
killed  plants  at  the  close  of  the  season. 

328.  Fungi  that  Infect  their  Host  from  Spores  Deposited 
On  the  Aerial  Parts  of  the  plant,  as  the  scab  of  the  apple  § 

*  Eurocystis  Cepula?.  t  Plasmidiophora  Brassicce. 

%  Peronospora  Schleideniana.  \  Fusicladium  dendriticum. 


Plants  as  Affected  by  Fungous  Parasites.          175 


and  pear,  and  the  downy  grape-vine  mildew  *  may  be 
held  in  cheek  by  applying  a  fungicide  (321)  to  the  host 
plant,  to  destroy  the  spores  as  they  alight  upon  it.  Vari- 
ous compounds  of  copper  and  of  sulfur  are  destructive 
to  the  spores  of  fungi,  and  when  properly  applied,  are 
harmless  to  the  plant.  The  copper  compounds  are  more 
generally  satisfactory,  since  they  have  the  greater  ad- 
hesive power. 


FIG.  78.  A  scab  spot  magni- 
fied.   (After  Trefease). 


FIG.  77.  Apple  affected  with  scab 
(the  dark  spots),  Fusicladium  den- 
driticum.  (After  Scribner). 


FIG.  79.  Section  through  a 
scab  spot,  highly  magnified.  The 
egg-shaped  parts  at  the  right  are 
the  spores.  (After  Trelease). 


329.  The  Bordeaux  Mixture,  which  consists  of  a  com- 
pound of  copper  sulfate  (324)  and  lime,  is  now  extensively 
used  to  prevent  many  fungous  diseases  of  this  class.  A 
standard  formula  for  the  Bordeaux  mixture  is : 

Dissolve  6  pounds  of  copper  sulfate  in  4  gallons  of  hot 
water  ;  in  another  vessel  slack  4  pounds  of  fresh  quick- 
lime in  4  gallons  of  (hot  or  cold)  water.  When  both  are 
cool,  pour  the  contents  of  the  two  vessels  together  and 

*  Peronospora  viticola. 


176  Principles  of  Plant  Culture. 

add  enough  water  to  make  45  gallons  of  the  whole.  Metal 
vessels,  other  than  those  of  brass  or  copper,  should  not 
be  used. 

The  hot  water  hastens  the  dissolving  of  the  copper 
sulfate.  Cold  water  may  be  used  by  suspending  the 
sulfate  in  it  in  a  sack  of  coarse  texture  a  day  or  two  in 
advance. 

Prepared  by  the  above  formula,  the  Bordeaux  mixture 
often  contains  more  lime  than  is  needed  for  the  chemical 
action  that  occurs.  To  avoid  this  excess  of  lime,  a  chem- 
ical test  may  be  used,  as  follows  :  Pour  only  half  of  the 
slacked  lime  and  water  into  the  copper-sulfate  solution, 
stir  well,  and  add  a  few  drops  of  a  20  per  cent  solution 
of  potassium  ferrocyanid.  If  a  rich,  reddish -brown  color 
is  produced,  add  more  lime.  Continue  to  test  and  add 
lime  until  the  reddish-brown  color  no  longer  appears. 
Then  add  a  little  more  lime,  as  a  slight  excess  of  lime  is 
desirable.  A  bright,  clean  knife  blade  may  also  be  used 
as  a  test.  If  a  slight  film  of  copper  forms  upon  it  when 
placed  in  the  mixture,  more  lime  is  needed.  The  Bor- 
deaux mixture  is  preferably  strained  before  use,  and 
should  be  kept  well  stirred  during  its  application.  It 
may  be  applied  with  any  good  spray  pump. 

The  arsenical  compounds  (284)  may  be  added  to  the 
Bordeaux  mixture,  and  thus  a  single  treatment  will  serve 
for  both  insects  and  fungi. 

330.  The  Diseases  Preventable  by  Bordeaux  Mixture  are 
the  apple  and  pear  scab  (328),  the  downy  mildew  and 
black  rot*  of  the  grape,  the  early  f  and  late  blight  J  of 
the  potato,  the  gooseberry  mildew,*  the  leaf- blight  of  the 
pear,f  and  some  others. 

*  L&stadia  BidwellH.  f  Macrosporium  Solani.  %  Phytophthora  infestans. 


Plants  as  Affected  by  Fungous  Parasites.          177 

In  all  these  diseases,  however,  the  treatment  is  preventive 
rather  than  curative.  The  first  application  should  be  made 
before  the  disease  appears  and  should  be  followed  occa- 
sionally by  others  as  new  foliage  is  formed  or  as  the 
material,  is  washed  off  by  rains. 

331.  Ammoniacal  Solution  of  Copper  Carbonate  possesses 
nearly  the  same  fungicidal  properties  as  Bordeaux  mix- 
ture,  but  adheres  less  strongly   to   foliage.      Being   a 
solution,  it  requires  no  straining  or  stirring,  and  it  leaves 
less  stain  on  drying  than  Bordeaux  mixture,  which  makes 
it  preferable  to  the  latter  for  use  upon  plants  of  which 
the   fruit   is  nearly   mature.      To   make  this  solution, 
dissolve  one  and  a  half  ounces  of  precipitated  copper 
carbonate  in  one  quart  of  strong  commercial  ammonia, 
and  add  25  gallons  of  water.     The  ammonia  should  be 
procured  in  a  glass  or  earthen  vessel,  which  should  be 
kept  tightly  corked.     To  prevent  waste  of  the  ammonia 
toy  evaporation,  prepare  immediately  before  spraying. 

332.  Potcissium-Sulfid  Solution   is  used  to  some  extent 
to  prevent  gooseberry  mildew  (330),  and  a  few  other 
diseases,  but  it  is  less  enduring  in  its  effects  than  the 
copper   compounds.      To   prepare   it,  dissolve   one-half 
ounce  of  potassium  sulfid  (sulfuret  of  potassium,  liver  of 
sulfur)  in  one  gallon  of  water  and  apply  immediately. 
The  sulfid  is  best  dissolved  in  a  little  warm  water  and 
then  diluted. 

333.  Moisture  Favors  Spore  Germination,  hence  a  free 
circulation  of  air  through  the  orchard  and  vineyard  tends 
to  prevent  fungous  diseases  by  absorbing  excessive  moist- 
ure (227).     Branches  of  fruit  trees  should  not  be  per- 

*  Sphcerotheca  Mors-uvce.       f  Entomosporium  maculatum. 


178  Principles  of  Plant  Culture. 

initted  to  hang  n.ear  the  ground,  and  weeds  should  be 
kept  down. 

Grapes  are  sometimes  inclosed  in  paper  bags  on  the 
vine,  to  keep  them  dry,  and  thus  preserve  them  from 
fungous  attack.  Grape  vines  sheltered  from  rains  by  a 
cornice  are  seldom  much  troubled  with  fungous  diseases. 

334.  Fungi  that   Develop  chiefly  on  the  Outside  of  the 
Plant  (epiphytic  (ep-i-phyt'-ic)  fungi), are  as  a  rule  readily 
controlled  by  sulfur,  either  in  the  form  of  flowers  of  sulfur, 
or  the  solution  of  potassium  sulfid  (332).     To  this  class 
belong  the  powdery  mildews  of  the  grape,*  apple, f  etc. 

335.  The   Cultivator   will   often   Need   to   Consult   the 
Specialist  in  dealing  with  fungous  diseases.     In  many 
cases,  it  will  be  difficult  or  impossible  for  him  to  decide 
as  to  the  exact  nature  of  a  given  trouble  without  careful 
training,  and  skill  in  the  use  of  the  compound  microscope. 
Specialists  in  this  line  are  now  employed  by  the  govern- 
ments of  most  civilized  nations  and  by  many  agricul- 
tural experiment  stations,  and  they  should  be  freely  con- 
sulted.    Much  may  be  learned,  however,  by  studying 
the  best  books  on  the  subject.     The  cultivator  should  be 

able  to  recognize  the  principal  fungous  diseases. 

i 

SECTION  VIII.     PLANTS  AS  AFFECTED  BY  WEEDS 

336.  Weeds  are  plants  of  the  higher  orders  that  persist 
in  growing  where  they  are  not  wanted.     They  injure  the 
desirable  plants  about  which  they  grow,  by  robbing  them 
of  light,  moisture  and  food,  and  their  presence  is  an  evi- 
dence of  slovenly  culture.     The  remarkable  vigor  and 
prolificacy  possessed  by  many  weeds  would  enable  them 

*  Uncinula  spiralis.  f  Podosphcera  oxycanthce. 


Plants  as  Affected  by  Weeds.  179 

to  soon  overcome  most  cultivated  plants,  but  for  the  aid 
of  the  cultivator.  As  with  harmful  insects  and  fungi, 
prompt  and  persistent  efforts  are  essential  to  the  control 
of  weeds  in  most  cultivated  grounds. 

337.  Annual,  Biennial  and  Perennial  Weeds.  With  ref- 
erence to  their  term  of  life,  weeds  and  other  plants  are 
divisible  into  three  classes,  viz.,  annual,  those  that  liv^e 
but  one  season;  biennial,  those  that  live  only  two  seasons j 
and  perennial,  those  that  live  an  indefinite  number  of  sea- 
sons. Weeds  of  the  first  class  usually  seed  most  abund- 
antly, and  hence  they  are  most  widely  distributed  and 
appear  in  cultivated  grounds  in  the  greatest  numbers. 
Those  of  the  third  class  are  commonly  most  tenacious  of 
life  and  are  therefore  often  most  difficult  to  control. 


FIG.  80.    Showing  how  plants  of  the  sow  thistle  multiply  from  under- 
ground stems. 

338.  Annual  and  biennial  weeds,  since  they  have  a  defi- 
nite life  period  and  multiply  almost  exclusively  by  seed, 
may  be  controlled  by  preventing  seedage.     To  accom- 
plish this  with  certainty,  the  plants  should  be  destroyed 
before  bloom,  as  many  species  possess  enough  reserve 
food  to  mature  seeds  sufficiently  for  germination,  if  cut 
while  in  flower. 

339.  Perennial  weeds  often  multiply  by  suckers  as  well 
as  by  seeds  (Fig.  80).     Since  the  roots  or  underground 


180  Principles  of  Plant  Culture. 

stems  whence  the  suckers  grow  (115),  are  hidden  be- 
neath the  soil  and  are  often  extremely  tenacious  of  life, 
weeds  of  this  class  are  frequently  very  hard  to  eradicate. 
Persistent  prevention  of  leafage,  by  starving  the  proto- 
plasm of  the  roots,  is  always  effectual,  though  it  is  often 
very  difficult  to  carry  out,  since  the  suckers  of  some 
species  grow  with  great  rapidity.  Yet,  on  the  whole,  no 
better  remedy  is  known.  Frequent  plowing  and  cultiva- 
tion of  the  infested  ground  is  usually  the  most  effectual 
means  of  preventing  leafage. 

Certain  very  tenacious  perennial  weeds,  as  the  Canada 
thistle  *  and  the  sow  thistle,  f  when  growing  on  deep,  rich 
loams  in  which  the  roots  spread  freely  below  the  plow 
line,  may,  it  is  said,  be  crowded  out  by  seeding  the  land  to 
grass,  at  less  cost  than  they  can  be  subdued  by  the  plow. 

If  we  have  mastered  the  foregoing  chapters,  we  are 
now  prepared  to  enter  upon  a  more  advanced  stage  of 
culture,  and  to  learn  how  to  cause  new  plants  to  grow, 
and  how  to  so  treat  the  plants  thus  grown  that  they  may 
best  serve  our  purpose. 


The  following  books  are  recommended  for  reading  in 
connection  with  the  preceding  chapter:  Elementary 
Meteorology,  Waldo;  Chemistry  of  the  Farm,  Waring- 
ton;  The  Spraying  of  Plants,  Lodernan;  Economic  En- 
tomology, Smith;  Fungous  Diseases  of  the  Grape  and 
Other  Plants,  Lamson-Scribner;  American  Weeds  and 
Useful  Plants,  Darlington. 

*  Cnicus  arvensis.  t  Sonchus  arvensis. 


CHAPTER  IV.     PLANT  MANIPULATION 

SECTION  I.     PLANT  PROPAGATION 

340.  Propagation,  as  the  term  is  generally  used  in 
plant  culture,  is  the  artificial  multiplication  of  plants, 
i.  e.,  reproduction  (16)   encouraged  or  induced  by  the 
knowledge,  skill  and  care  of  the  cultivator. 

Theoretically,  any  part  of  a  plant  containing  living 
protoplasm,  with  sufficient  prepared  food  or  tissue  capa- 
ble of  preparing  food  (59),  may  under  proper  conditions 
develop  into  a  complete  plant.  But  in  practice,  we  have 
not  been  able  to  fully  demonstrate  this  theory;  for  exam- 
ple, the  roots  and  leaves  of  some  plants  have  not  been 
induced  to  form  buds. 

341.  Plants  are  Propagated  by  Numerous  Methods,  but 
only  two  of  these  are  distinct  in  kind,  viz.,  by  seeds  (or 
spores),  and  by  division  of  the  plant.    -In  propagation  by 
seeds,  the   embryo   of  the  seed  (54)  is  the   vital   center 
whence  the  new  plant  is  developed.      In  propagation  by 
division,  a  living  bud  (128)  from  the  parent  plant,  or  a 
bit  of  tissue  capable  of  forming  a  bud,  is  substituted  for 
the  embryo  of  the  seed.    In  seed  propagation,  the  result- 
ing plant  is  the  product  of  sexual  fecundation  (150),  and 
hence  cannot   be  considered  as  strictly  a  part  of  the 
parent.     It   does   not  necessarily  resemble   the   parent 
closely.     In  propagation  by  division,  on  the  other  hand, 
the  resulting  plant  may  be  regarded  as  simply  a  contin- 
uation of  the  growth  of  the  parent  in  a  new  location,  and 
generally  closely  resembles  the  parent. 

(181) 


182  Principles  of  Plant  Culture. 

342.  Propagation  by  Seeds  is  commonly  practiced  with 
annual  and  biennial  plants  and  with  perennials  in  which 
the  reproduction  of  the  exact  parental  form  is  unimport- 
ant, as  in  the  cereals,  forest  trees  and  seedlings  intended 
for  grafting.     This  method  is  also  used  when  variation 
in  the  progeny  is  desired,  as  in  developing  new  varieties 
(438  b). 

343.  Propagation  by  Division  of  the  plant  is  used  when  it 
is  desired  to  reproduce  the  exact  parental  form,  as  in  fruit- 
and  the  finer  ornamental  trees,  many  flowering  plants, 
etc. ;  in  certain  plants  that  are  more  readily  multiplied 
by  division  than  by  seeds,  as  mint  and  many  other  per- 
ennial herbs;  and  in  other  plants  that  rarely  or  never 
produce  seed,  as  the  horse-radish,  sugar  cane,  banana,  etc. 

A  —  PROPAGATION  BY  SEEDS 

344.  This  is  the  most  common  method  of  propagating 
plants.      It  seemed  appropriate  to  give  nearly  all  of  the 
needed  directions  for  planting  seeds  in  the  first  two  sec- 
tions  of  Chapter   II.     We   add,  therefore,  only   a  few 
general  rules  deduced  from  the  principles  there  stated. 

a  —  The  soil  in  which  seeds  are  to  be  planted  should  be 
thoroughly  crumbled,  because  the  seeds  must  have  access 
to  the  oxygen  of  the  air,  or  they  cannot  germinate  (31). 

b  —  The  well-crumbled  soil  should  be  compactly  pressed 
about  the  seeds,  because  the  seeds  cannot  absorb  moisture 
rapidly  unless  the  seed-case  is  in  contact  with  the  moist 
soil  particles  at  many  points  (27  b). 

c  —  The  soil  should  be  moist,  but  not  wet  enough  to  puddle 
(31);  otherwise  the  oxygen  is  likely  to  be  shut  out  from 
access  to  the  seeds  (35). 


Propagation  by  Division.  183 

d  —  Seeds  should  be  planted  no  deeper  than  is  necessary  to 
insure  the  proper  degree  of  moisture;  otherwise  the  plantlet 
expends  a  needless  amount  of  energy  in  reaching  the 
surface  (51,  48).  Very  small  seeds  should  be  only  slightly 
covered,  if  at  all,  and  must  receive  artificial  watering 
when  necessary  (52).  Spores  must  not  be  covered  with 
soil  at  all  (53). 

B  —  PROPAGATION  BY  DIVISION. 

345.  We  have  seen  that  a  part  of  a  plant,  placed  under 
favorable  conditions,  is  usually  capable  of  developing  into 
a  complete  plant  (340).  A  section  or  cutting  of  the  stem, 
for  example,  that  has  no  roots  at  the  time  it  is  cut  off, 
may  be  caused  to  form  roots,  and  thus  become  a  complete 
plant.  A  cutting  of  a  root  may  also  put  forth  a  bud, 
which  in  turn  may  develop  into  a  shoot,  and  form  leaves, 
flowers  and  fruit.  Again,  we  have  seen  that  portions  of 
cambium  from  different,  nearly -related  plants  may  unite 
by  growth  (70),  which  enables  us  to  change  undesirable 
sorts  into  valuable  ones  by  grafting  (383).  These  and 
certain  other  methods  of  multiplying  plants,  come  under 
propagation  by  division. 

In  propagation  by  division ,  the  presence  of  at  least  one 
healthy  growing  point  (67)  in  the  part  selected  for  the  propa- 
gation is  generally  essential  to  success  and  is  always  helpful. 

The  processes  treated  in  this  and  the  two  succeeding 
sections  may  be  likened  to  surgical  operations  in  medi- 
cine. If  plants  are  less  highly  organized  and  possess  less 
of  sensibility  than  the  higher  animals,  they  are,  none  the 
less,  living  beings.  Violent  operations,  if  necessary,  should 
always  be  performed  with  this  truth  in  mind.  Needless 


184  Principles  of  Plant  Culture. 

injury  and  careless  handling  in  the  treatment  of  plants  are 
always  to  be  avoided. 

346.  Two  Methods  of  Propagation  by  Division  may  be 
distinguished,  viz.,  by  parts  intact  and  by  detached  parts. 
In  the  first,  the  part   selected    for  propagation  is  not 
separated  from  the  parent  until  the  organs  needed  to 
make  it  self-supporting  are  formed;  or  if  a  cion  (386), 
until  it  has  united  to  the  part  on  which  it  is  intended  to 
grow.     In   the   second   method,  the   part   intended   for 
propagation  is  severed  from  the  parent  at  the  outset  and 
placed  under  conditions  favoring  the  formation  of  the 
organs  needed  to  make  it  self-supporting;  or  if  a  cion, 
favoring  its  union  with  the  stock  (383). 

A— PROPAGATION    BY    PARTS    INTACT. 

This  method  is  applicable  to  many  plants  and  has  the 
advantages  of  being  reliable  and  requiring  little  skill. 
The  part  selected  for  propagation,  being  nourished  by  the 
parent  until  it  forms  the  needful  organs,  is  able  to  endure 
unfavorable  conditions  that  would  prove  fatal  in  most 
other  methods  of  propagation.  This  method  includes 
four  divisions,  viz.,  propagation  by  suckers (34 7), by  stolons 
(348),  by  layers  (349),  and  by  approach  grafting  (399).  In 
the  first  two,  the  propagation  is  performed  by  the  parent 
plant  without  other  aid  than  the  maintenance  of  a  well- 
aerated,  moist  and  clean  soil  that  stimulates  the  produc- 
tion of  the  needed  organs,  which  in  these  cases  are  roots. 

347.  Propagation  by  Suckers.    Suckers  are  shoots  that 
originate  from  roots  or  underground   stems  and  grow 
upward,  forming  young  plants  about  the  parent,  as  in  the 
blackberry,  plum,  choke- cherry,  etc.      The  propagation 


Propagation  by  Parts  Intact. 


185 


consists  in  simply  cutting  off  the  root  or  underground 
stem  whence  the  sucker  proceeds,  and  transplanting  the 
latter. 

The  growth  of  suckers  may  generally  be  stimulated  in 
plants  that  naturally  produce  them,  by  cutting  off  the 
roots  or  underground  stems  from  which  they  grow,  or  by 
severely  pruning  the  top. 

The  propagation  of  woody  plants  from  suckers  is  not, 
as  a  rule,  considered  wise,  since  the  roots  are  usually 
poorly  developed  in  proportion  to  the  stem,  and  some 
plants  grown  in  this  manner  seem  to  acquire  the  tendency 


FIG.  81.  FIG.  82. 

Fig.  81.  Sucker  plants  of  the  red  raspberry,  Rubus  strigosus.  A,  before 
growth  has  started;  B,  after.  The  two  shoots  of  B  starting  just  above  the 
roots  form  the  new  canes. 

Fig.  82.  Tip  plant  of  black  raspberry.  The  bud,  whence  the  young 
shoot  starts,  appears  at  the  base  of  the  parent  cane.  (After  Bailey). 

to  form  suckers  excessively.  In  the  red  raspberry  *  and 
the  blackberry,  f  however,  propagation  by  suckers  is  the 
most  convenient  method,  and  it  appears  to  be  followed 
by  no  bad  results  (Fig.  81). 

348.  Propagation  by  Stolons.  A  stolon  is  a  branch 
that  starts  above  or  at  the  surface  of  the  ground  and 
either  grows  prostrate  or  curves  downward  till  it  reaches 

*  Rubus  strigosus,  J?.  Idceus.  -f-  JR.  villosus. 

12 


186  Principles  of  Plant  Culture. 

the  ground,  where  it  takes  root,  usually  at  the  nodes 
(116).  The  currant,  juneberry,  cranberry  and  many 
herbaceous  plants  are  readily  multiplied  in  this  way. 
Stolons  often  root  without  assistance,  but  the  rooting  is 
much  hastened  and  encouraged  by  covering  the  branch 
with  soil.  When  well  rooted,  the  young  plants  may  be 
separated  from  the  parent  by  cutting  the  stolons. 

Woody  plants  grown  from  stolons  are  seldom  uniform 
in  size  and  are  not  often  as  well  rooted  as  those  grown 
from  cuttings  (358).  Some  herbaceous  plants  are,  how- 
ever, more  readily  propagated  by  stolons  than  by  any 
other  means. 

The  offset  by  which  the  houseleek  *  is  so  readily  prop- 
agated, is  a  very  short  stolon  that  forms  a  single  tuft  of 
leaves  at  its  apex.  The  cane  of  the  black -cap  raspberry,  f 
which  roots  from  the  tip  (Fig.  82),  and  the  runner  of  the 
strawberry  (Fig.  83),  that  forms  a  plant  at  each  alternate 
node,  are  modified  stolons. 

349.  Propagation  by  Layers  or  Layering.  The  layer  is 
an  artificial  stolon,  i.  e. ,  a  branch  that  does  not  naturally 

grow  downward, 
which  is  covered  with 
o  r  surrounded  b  y 
moist  soil  to  stimulate 
the  production  o  f 
roots  (89).  The 
branch  may  be  bent 

FIG.  as.    Runner  of  the  strawberry.  down  and   covered,  as 

is  usually  practiced  with  the  grape,  wisteria  etc.,  or  the 
soil  may  be  ridged  up  about  the  branch,  as  is  done  with 

*  Sempervivum .  t  JRubus  occidentalis. 


Propagation  by  Parts  Intact. 


187 


the  quince  and  paradise  apple.  In  either  case,  the  ter- 
minal portion  of  the  stem  is  commonly  left  uncovered. 
In  the  latter  method,  which  is  known  as  mound-layering 
(Fig.  84),  the  stems  of  the  plant  to  be  layered  are  usu- 
ally cut  off  just  above  the  surface  of  the  ground  in  early 

spring,  to  stimulate  the  for- 
mation of  vigorous  shoots, 
which  are  ridged  up  about 
midsummer  or  preferably  not 
until  the  succeeding  fall  or 
spring.  The  ridging  should 
be  sufficiently  high  to  cover 
FIG.  84.  Mound-layering  of  goose-  several  of  the  lower  nodes 

berry  plants.    (After  Bailey).  (n6)>       ^^    grQW    out    ^ 

the  nodes  and  the  shoots  are  usually  well  rooted  by  the 

autumn  following  the  ridging. 

Many  woody  plants  that  do  not  readily  form 
roots  when  layered,  may  be  induced  to  do  so 
by  mutilating  the  stem 
somewhat  in  the  cover- 
ed part.  This  tends  to 
restrict  the  growth  cur- 
rent (80)  and  causes  an 
accumulation  of  reserve 
food,  from  which  roots 
may  grow.  Girdling, 
twisting,  bending  o  r 
spliting  the  stem  for  a 

FIG.  85.    Layered  branch  of  currant,  split 
to  encourage  the  formation  of  roots.  Short  distance  Will  often 

have  the  desired  effect  (Fig.  85). 

Layering  is  a  very  reliable  and  expeditious  method  of 
propagating  many  woody  and  herbaceous  plants. 


188  Principles  of  Plant  Culture. 

350.  Propagation  by  Division  of  the  Crown  of  the  plant, 
which  is  practicable  with  many  perennial  herbs,  as  the 
rhubarb,  dahlia,  globe  artichoke  etc.,  though  not  strictly 
analogous  to  propagation  by  stolons  or  layers,  may  be 
considered  here.     It  consists  in  taking  up  the  plant,  pre- 
ferably while  dormant,  and  cutting  the  crown  into  two 
or  more  parts,  according  to  its  size  or  the  number  of 
plants  desired,  and  planting  the   divisions  as  separate 
plants.     This  method  is  applicable  to  propagation  for 
private  use,  rather  than  for  sale  purposes. 

Propagation  by  approach  grafting,  although  in  order 
here,  is  more  readily  treated  with  the  other  methods  of 
grafting  (399). 

B  — PROPAGATION  BY  DETACHED  PARTS. 

This  comprises  two  different  modes  of  propagation, 
viz. ,  by  specialized  buds  and  by  sections  of  the  plant. 

a~  Propagation  by  Specialized  Buds. 

351.  This  includes  propagation  by  bulbs,  bulblets,  corms 
and  tubers.     It  is  in  a  sense  intermediate  between  prop- 
agation by  parts  intact  (346)  and  by  cuttings  (358).   The 
bud  that  is  to  form  the  future  plant,  though  not  having 
roots  of  its  own,  has  been  specially  prepared  by  the 
parent,  through  an  abundant  food  supply  and  a  partially 
dormant  condition  of  the  protoplasm,  to  maintain  a  sep- 
arate existence,  even  under  adverse  conditions,  and  in 
due  time  to  develop  into  a  plant.     In  these  respects  it 
resembles  the  seed,  from  which  it  differs,  however,  in  the 
less  dormant  condition  of  its  protoplasm  and  in  not  being 
the  product  of  sexual  fecundation  (341). 


Propagation  by  Detached  Parts. 


189 


352.  The  Bulb  is  a  very  short  stem  containing  a  ter- 
minal bud  inclosed  in  scales  (128).  The  scales  are  thick- 
ened by  a  store  of  food,  and  in  their 
axils  are  smaller  lateral  buds.  The 
terminal  bud  usually  develops  into 
a  flower,  and  then  perishes.  One  or 


FIG.  86.  PIG.  87.  FIG.  88.  FIG.  89. 

Fig.  86.  Bulb  of  the  common  onion,  Allium  cepa,  divided  lengthwise. 
B,  buds. 

Fig.  87 >  Bulb  of  garlic,  Allium  sativum.  It  contains  several  smaller 
bulbs  (cloves). 

Fig.  88.    Bulb  of  wild  lily. 

Fig.  89.    The  same  divided  lengthwise,  showing  buds,  B. 

more  of  the  lateral  buds  may  develop  into  flower-buds 
for  the  next  year,  and  thus  continue  the  life  of  the  plant, 
as  in  the  common  onion  (Fig.  86);  or  the  lateral  buds 
may  develop  at  the  expense  of  the  parent,  as  in  the  po- 
tato onion. 

353.  Bulbletsor 
B  u  I  b  e  I  s  are  small 
bulbs  formed  in  the 
axils  of  the  leaves  in 
certain  plants,  as  the 
tiger  lily,*  (Fig.  90), 

FIG.  90.    Bulblets  in^ls  of  leaves  of  tiger  Of  at  the  aP6X  °f  the 

my.  stem,  as  in  the  "top" 

or  bulb-bearing  onion  (Fig.  91). 

*  Lilium  tigrinmn. 


190  Principles  of  Plant  Culture. 

354.  The  Corm  (Fig.  92)  differs  from  the  bulb  chiefly 
in  being  without  scales.  The  food  is  deposited  in  the 

thickened  stem.  The 
conns  of  onr  flowering 
plants,  as  the  croc  us.  cyc- 
lamen etc.,  are  general- 
ly called  bnlbs  in  com- 
merce. 

355.  The  Tuber,of  which 
FIG.  91.  Buibiets     FIG.  92.    Corm  of  the  common  potato  is  the 

of    "top"    onion,    crocus     with     small  mogt    famiUaj.    example, 

sometimes  used  as    corms  (buds)  for  fol- 

onion  "  sets."  lowing  year.  differs    from   the  COrni  ill 

being  the  end  of  an  underground  branch  of  the  stem 
(115),  instead  of  developing  in  direct  contact  with  the 
parent.  It  also  has  more  numerous  buds  (eyes)  than  the 
corni.  * 

356.  Propagation  from  Bulbs,  BulbIets,Corms  and  Tubers 
is  a  very  simple  operation  and  consists  merely  in  plant- 
ing these  parts  in  the  place  where  the  plants  are  desired. 
Tubers  may  be  cut  into  pieces  containing  one  or  more 
buds  each,  if  desired.  The  rules  given  for  planting  seeds 
(344)  apply  equally  well  here.  All  should  be  stored  for 
preservation  in  a  cool,  moderately  dry  place,  that  is  free 
from  frost.  They  retain  their  vitality  but  a  single 
year. 

In  the  methods  of  propagation  thus  far  considered, 
with  the  sole  exception  of  layering  (349),  advantage  has 
been  taken  of  a  natural  mode  of  plant  multiplication. 
The  skill  of  the  cultivator,  however  much  it  may  assist 
the  processes,  is  not  necessary  to  their  success,  since  wild 
plants  habitually  increase  by  the  same  methods.  We 
will  now  consider  a  method  which  is  less  often  illustrated 


Propagation  by  Cuttings.  191 

in  nature,  and  in  which  the  skill  and  care  of  the  cultiva- 
tor are,  as  a  rule,  essential  to  its  accomplishment,  viz. : 

b  ~  Propagation  by  sections  of  the  plant. 

The  various  methods  of  propagation  in  this  division 
are  alike  in  the  fact  that  a  detached  part  of  the  parent 
plant,  containing  living  protoplasm,  is  placed  for  a  time 
under  specially  favorable  conditions,  in  virtue  of  which 
the  part  is  enabled  not  only  to  live,  but  to  perform  its 
functions  and  reproduce  the  needed  organs;  or  if  a  cioii 
(386),  to  unite  by  growth  to  the  part  with  which  it  is 
placed  in  contact. 

357.  In  propagation  by  sections  of  the  plant  we  must, 
of  necessity,  wound   the    plant  tissues  in  securing  the 
parts  for  propagation.      Since  it  is  always  desirable  that 
the  wound  should  heal  promptly  (73),  it  is  important  that 
the  cutting  tools  used  should  have  sharp  and  xmooth  edges. 

As  here  considered,  propagation  by  sections  of  the 
plant  includes  two  methods,  differing  materially  in  their 
requirements  and  in  the  manner  of  development  of  the 
plants,  viz. ,  propagation  by  cuttings  and  by  grafting. 

a  —  Propagation  by  Cuttings. 

358.  A  Cutting  is  a  detached  member  of  a  plant,  in- 
tended to  be  placed  in  the  soil  or  some  other  medium  for 
propagation.     It  may  be  in  an  active  or  a  dormant  state 
(13),  and  may  or  may  not  contain  a  growing  point  (67). 
Before  the  cutting  can  become  a  plant,  it  must  develop 
the  essential  part  or  parts  of  the  plant  that  it  lacks;  i.  e., 
the  stem  and  the  leaves,  or  the  root,  or  all  these  mem- 
bers.     Cuttings  of  the  stem  are  usually  planted  with 


192  Principles  of  Plant  Culture. 

their  proximal  end  (116)  in  the  soil,  and  their  distal  end 
in  the  air.  Root  cuttings  are  generally  covered  in  the 
soil. 

359.  Nearly  All  Plants  may  be  Propagated  by  Cuttings 
from  one  or  another  of  their  parts.    The  ease  with  which 
plants  may  be  multiplied  in  this  way  varies  greatly  in 
different  species  (21),  and  even  in  different  varieties  of 
the  same  species.     The  appearance  of  a  plant  does  not 
always  indicate  the  facility  with  which  it  may  be  grown 
from  cuttings;  the  only  sure  way  to  ascertain  this  is  by 
trial. 

Climate  exerts  a  marked  influence  upon  the  tendency 
of  plants  to  develop  from  cuttings.  In  certain  locations 
in  southern  Europe  and  in  parts  of  South  America, 
branches  of  the  common  apple  tree,  sharpened  and  driven 
into  the  ground  as  stakes,  often  take  root  and  sometimes 
even  bear  fruit  during  the  same  season.  A  warm,  moist 
atmosphere  is  very  favorable  to  propagation  by  cuttings. 

We  have  seen  that  the  roots  of  certain  plants  normally 
develop  buds  (131).  In  like  manner,  the  stems  of  many 
plants,  as  the  potato,  grape  etc.,  normally  develop  grow- 
ing points  of  roots  at  their  nodes  (116).  Plants  that  nor- 
mally develop  buds  upon  their  roots,  or  growing  points  of 
roots  at  their  nodes,  are  readily  propagated  by  cuttings.  But 
propagation  by  cuttings  is  not  limited  to  such  plants 
(362). 

360.  The  Essential  Characteristics  of  a  Cutting  are  a  — 
a  certain  amount  of  healthy  tissue;  b  —  a  certain  amount 
of  prepared  food,  or  of  tissue  capable  of  preparing  food 
(59);  c — in  most  species,  a  growing  point  (67),  either  of 
the  stem  or  root,  or  of  both. 


Propagation  by  Cuttings.  193 

3(51.  The  Parts  of  plants  to  be  Used  for  Cuttings,  there- 
fore, are  preferably  the  younger,  matured  growths,  since 
the  tissues  of  these  are  most  vigorous;  or  else  a  part  that 
possesses  a  certain  amount  of  healthy  and  vigorous  leaf 
tissue.  .The  cutting  should  always  contain  one  or  more 
buds  when  practicable  (128). 

362.  Conditions   that   Favor   the   Growth    of  Cuttings. 

a  —  A  soil  warmer  than  the  air  above  it  (  "bottom  heat"  ) 
is  important  in  growing  many  plants  from  cuttings. 
Warmth  stimulates  plant  growth,  and  when  applied  to 
one  part  of  a  plant,  it  stimulates  growth  in  that  part.  If 
the  soil  about  a  planted  cutting  is  warmed  to  a  tempera- 
ture considerably  higher  than  that  of  the  air  above,  the 
growth  of  roots  is  stimulated.  Indeed  bottom  heat  often 
excites  growth  in  cuttings  that  will  not  grow  without  it. 

b  —  A  comparatively  low  air  temperature  is  important  in 
growing  many  plants  from  cuttings  of  the  stem  (377), 
because  it  is  essential  that  the  stem  growth  be  held  in 
check  until  roots  are  formed.  A  soil  temperature  of 
about  65°  F.,  with  an  air  temperature  about  fifteen 
degrees  lower,  is  suited  to  the  great  majority  of  plants 
usually  propagated  under  glass  from  cuttings.  It  is 
important  that  these  temperatures  be  maintained  nearly 
constant  until  roots  have  developed. 

Since  we  have  better  facilities  for  raising  than  for 
lowering  the  natural  temperature  of  the  atmosphere, 
propagation  from  cuttings  is  easiest  at  a  time  of  the  year 
when  the  temperature  of  the  atmosphere  during  the  day 
does  not  much  exceed  50°.  By  observing  special  pre- 
cautions, however,  it  is  possible  to  propagate  many  plants 
from  cuttings  during  the  warm  season. 


194  Principles  of  Plant  Culture. 

c  —  Abundant  moisture  is  important  in  growing  plants 
from  cuttings,  because  moisture  favors  root  development 
(89),  and  water  is  essential  to  cell  growth  (63).  The 
amount  of  water  required  varies  considerably  with  differ- 
ent plants  and  conditions. 

With  cuttings  containing  leaf  tissue  (377,  382),  trans- 
piration (75)  must  be  reduced  to  the  minimum  until 
roots  are  formed,  because  water  cannot  be  taken  up  freely 
without  root-hairs  (101).  For  such  cuttings,  therefore, 
the  air  as  well  as  the  soil  must  be  kept  abundantly  moist 
(369),  and  the  direct  rays  of  the  sun  must  be  intercepted 
by  shading  (236). 

363.  Methods  for  Controlling  Temperature.     The  alter- 
nations of  temperature  in  the  open  air  are  unfavorable 
to  the  development  of  cuttings,  though  many  plants,  as 
the  willow,  grape  and  currant,  are  readily  propagated 
from  cuttings  out  of  doors.     Some  structure,  therefore, 
that   may  confine  warmth  radiated  from  the  earth  or 
artificially  generated,  or  that  may  when  necessary  shut 
out  a  part  of  the  solar  heat,  is  always  of  great  assistance 
in  propagating  plants  from  cuttings,  and  in  many  species 
is  essential  to  success.     Since  light  is  necessary  to  food 

preparation  (59)? 
such  a  structure 
must  be  roofed 
with  glass  or  some 
other  more  or  less 
transparent  ma- 

FiG.93.  Cold-frame, with  sash  lifted  for  ventilation,  terial. 

364.  The  Cold-Frame  (Fig.  93)  is  the  simplest  structure 
of  this  kind.      It  consists  of  a  frame  or  box  without 
bottom,  usually  shallower  on  one  side  than  on  the  other, 


Propagation  by  Cuttinf/x.  195 

covered  with  glazed  window  sash.*  The  frame  is  gen- 
erally placed  so  that  its  shallower  side  faces  the  south, 
thus  giving  its  cover  a  southward  slope.  It  has  no 
provision  for  artificial  heat,  though  when  covered  with 
glass,  the  temperature  within  the  frame  is  much  increas- 
ed during  sunshine,  owing  to  the  property  possessed  by 
glass  of  confining  the  heat  rays.  The  cold  frame  should 
be  protected  in  freezing  weather  by  an  additional  cover 
of  mats  or  blankets,  while  excessive  sun  heat  should  be 
avoided  by  shading  (236).  Muslin-  or  paper-covered 
frames  require  no  shading. 

Although  affording  no  bottom  heat  (362  a),  the  cold- 
frame  may  be  used  for  propagating  many  plants  from 
cuttings.  It  is  also  serviceable  in  connection  with  the 
propagating  bed  (368)  for  "  hardening  off"  young  plants 
grown  from  cuttings  in  the  latter,  as  well  as  for  growing 
many  plants  from  seed.  Set  over  a  pit  in  the  earth,  the 
cold-frame  makes  an  excellent  place  (cold  pit)  for 
wintering  half-hardy  plants. 

365.  The  Hotbed  differs  from  the  cold-frame  in  having 
bottom  heat  (362  a),  which  is  usually  supplied  by  the 
fermentation  of  moist  vegetable  material,  as  horse  manure, 
leaves,  refuse  hops  or  tan-bark.  The  material  intended 
for  heating,  if  fresh,  should  be  thrown  into  a  pile  of 
sufficient  size  to  generate  heat  several  days  before  it  is 
desired  for  use;  and  unless  already  moist,  it  should  be 
moderately  sprinkled  with  water.  In  order  that  all  the 
material  may  reach  the  same  stage  of  fermentation,  the 
mass  should  be  made  into  a  new  pile  after  the  heating 

*  Muslin  or  paper  is  sometimes  used  instead  of  glass,  and  these  mate- 
rials maybe  rendered  waterproof  and  less  opaque  by  painting  with  linseed 
oil  or  some  similar  material. 


196 


Principles  of  Plant  Culture. 


starts  vigorously,  as  is  indicated  by  vapor  rising  from 
the  heap,  and  the  outer  part  of  the  mass  should  be  placed 
in  the  center  of  the  new  pile.  Leaves  ferment  slower 
than  the  other  materials  above  named,  and  hence  may 
often  be  advantageously  mixed  with  them  to  lengthen 
the  period  of  fermentation. 

Heat  is  economized  by  placing  the  fermenting  material 
in  a  pit  in  the  ground,  but  hotbeds  are  often  made  above 

ground.  The  hot- 
bed pit  should  be 
in  a  well-drain- 
ed and  sheltered 
place,  and  two 
to  two  and  one- 
half  feet  deep. 
In  this  the  heat- 

FIG.  94.  Cross- section  of  hotbed  in  pit.  The  frame    ing    material 
is  banked  up  a  little  with  earth.  (After  Greiner).       g^ould    ^6   mO(j_ 

erately  packed,  until  the  pit  is  nearly  or  quite  full.  The 
frame  may  then  be  placed  over  the  pit,  after  which  the 
heating  material  should  be  covered  with  soil  and  the  sash 
put  011  to  confine  the  warmth.  Within  a  few  days  after 
covering  with  the  sash,  the  fermenting  material  usually 
generates  a  rather  violent  heat,  which  should  be  per- 
mitted to  decline  to  about  90°  F.,  before  planting  seeds 
or  cuttings  in  the  hotbed.  The  same  protection  against 
excessive  heat  or  cold  is  used  as  for  the  cold-frame;  but 
the  hotbed  requires  much  more  care  in  ventilation,  since 
the  heating  material  generates  vapor  and  carbonic  acid 
as  well  as  heat,  and  these  when  present  in  excess  are 
-detrimental  to  plant  growth. 


Propagation  by  Cuttings. 


197 


366.  The  Greenhouse  is  an  expansion  of  the  hotbed, 
i.  e.,  a  structure  sufficiently  large  so  that  it  may  be 
entered,  and  arranged  for  heating  by  fire.*  In  temperate 
climates,  greenhouses  are  usually  constructed  12  to  22 
feet  wide,  with  a  gable  or  M  roof,  having  a  slope  of  35° 
to  40°,  covered  with  glass  and  with  the  ridge  or  ridges 
extending  north  and  south  (Fig.  95);  but  in  very  cold 
climates  a  shed  roof  facing  the  south  is  preferable. 
Greenhouses  are  often  built  with  one  slope  of  the  roof 
longer  and  less  steep  than  the  other,  and  with  the  ridge 
extending  east 
and  west.  Such 
a  roof  is  called 
a  "two- thirds" 
or  "three-quar- 
ters span, ' '  ac- 


cording as  the 

lono-er    Slope    FlG'  95*  Cross-section  of  greenhouse.  (After  Greiner). 

covers  two- thirds  or  three-quarters  of  the  width  of  the 
house.  The  long  slope  usually  faces  the  south,  but  houses 
have  recently  been  built  with  the  shorter  and  steeper 
slope  facing  the  south,  a  plan  thought  to  possess  advan- 
tages for  growing  certain  plants,  as  carnations. 

Provision  is  made  for  ventilation  in  glass  houses  by 
placing  a  certain  number  of  movable  sash  in  the  roof  or 
elsewhere.  In  order  that  the  glass  may  not  be  far  above 
the  plants,  the  side  walls  should  not  exceed  five  feet  in 
height  (241).  These  may  be  of  wood,  but  a  wall  of  brick, 
ten  inches  thick,  with  a  two-inch  air  space  in  the  center, 
is  preferable,  since  this  better  economizes  heat.  The 
furnace  and  potting  rooms  obstruct  the  light  least,  and 

*  Hotbeds  are  now  being  heated  by  fire  to  some  extent. 


198  Principles  of  Plant  Culture. 

afford  the  most  protection,  when  located  to  form  the  north 
wall  of  the  house.  In  houses  extending  north  and  south, 
the  south  end  is  usually  glazed  above  the  height  of  the 
side  walls. 

367.  Heating  Devices  for  the  Greenhouse  are  of  various 
kinds.  The  "smoke  flue'7  is  simplest  and  cheapest  in 
first  cost.  It  consists  of  a  flue  extending  from  the  furnace, 
which  is  placed  somewhat  below  the  floor  level,  length- 
wise through  the  house,  preferably  rising  gradually  to  a 
chimney  at  the  opposite  end;  or  the  flue  may  cross  the 
farther  end  of  the  house  and  return  at  the  other  side,  to 
a  chimney  built  directly  upon  the  furnace.  The  latter 
method  usually  gives  better  draft,  since  the  warmth  from 
the  furnace  stimulates  an  upward  current  of  air  through 
the  chimney.  The  flue  should  be  of  brick  for  the  first  25 
feet  from  the  furnace,  as  a  safeguard  from  fire.  After 
this  it  may  be  of  cement,  or  of  vitrified  drain- pipe. 

Greenhouses  of  the  better  class  are  now  almost  invari- 
ably heated  with  steam  or  hot  water,  or  with  a  combina- 
tion of  the  two.  Pipes  from  a  boiler  located  beneath 
the.  floor  level,  extend  nearly  horizontally  about  the 
house,  below  the  benches,  returning  to  the  boiler;  or 
the  main  feed  pipe  extends  overhead  to  the  farther  end 
of  the  house,  where  it  connects  with  a  system  of  return 
pipes  beneath  the  benches.  While  the  steam-  or  hot- 
water  heating  costs  much  more  at  the  outset  than  the 
smoke-flue  system,*  it  is  generally  found  not  less  eco- 
nomical and  far  more  satisfactory  in  the  long  run.  Where 


*  In  round  numbers,  the  cost  of  the  smoke-flue  may  be  estimated  at  ten 
per  cent  of  the  whole  outlay  required  in  a  house  heated  by  this  method, 
while  in  one  heated  with  hot  water  or  steam,  the  cost  of  the  heating  appa- 
ratus is  not  far  from  fifty  per  cent  of  the  whole. 


Propagation  by  Cuttings.  199 

the  pipes  need  to  make  many  turns,  steam  is  usually 
more  satisfactory  than  hot  water. 

368,  The  Propagating  Bed.  A  certain  part  of  the 
greenhouse  is  usually  set  apart  for  propagating  plants 
from  cuttings.  The  propagating  bed  is  made  upon  the 
ordinary  greenhouse  bench,  directly  over  the  flue  or  heat- 
ing pipes.  To  furnish  the  bottom  heat  (362  a),  the  space 
beneath  the  bench  is  boxed  in  with  boards.  Horizontal 
doors  are,  however,  provided  which  may  be  opened  when 
it  is  desirable  to  allow  a  part  of  the  heat  to  pass  directly 
into  the  house.  The  floor  of  the  bench  should  not  be  so 
tight  as  to  hinder  drainage. 

In  large  commercial  establishments,  entire  glass  houses 
are  often  devoted  solely  to  propagation.  Such  houses 
are  usually  eleven  or  twelve  feet  wide,  with  low  side 
walls.  Sometimes  lean-to  houses  are  built  for  propaga- 
tion, on  the  north  side  of  a  wall,  where  direct  sunlight 
is  cut  off". 

In  making  the  propagating  bed,  a  thin  layer  of  sphag- 
num moss  is  usually  spread  over  the  floor  of  the  bench 
and  covered  to  a  depth  of  two  to  four  inches  with  well- 
packed,  clean,  rather  coarse  sand,  brickdust  or  powdered 
charcoal.  Sometimes  the  whole  bed  is  made  of  moss. 
These  materials  are  used  because  they  will  not  retain  an 
excess  of  water  if  the  proper  provision  is  made  for  drain- 
age. Sand  is  most  used  because  it  is  as  a  rule  readily 
obtained,  but  it  needs  to  be  selected  with  care,  as  it  often 
contains  injurious  mineral  matters.  Sand  found  along 
the  borders  of  fresh- water  streams  or  lakes  may  gener- 
ally be  used  without  washing,  but  that  dug  from  sandpits 
should  in  most  cases  be  exposed  to  the  air  for  a  few 


200 


Principles  of  Plant  Culture. 


weeks,  and  then  be  thoroughly  washed  before  being  em- 
ployed for  cuttings.  The  same  sand  should  be  used  for 
but  one  lot  of  cuttings,  as  a  rule,  for  it  is  liable  to  become 
infested  with  fungi  that  may  work  havoc  with  cuttings 
placed  in  it. 

369.  Methods  of  Controlling  Humidity.     Where  moist- 
ure needs  to  be  controlled  with  especial  care,  as  in  prop- 
agating delicate  plants  from  green  cuttings,  or  in  herba- 
ceous grafting  (393),  the  planted  cut- 
tings or  the  grafted  plants  are  often 
covered    with    bell -jars.      To    guard 
against  sudden  fluctuations  in  temper- 
ature, a  larger  bell -jar  is 
sometimes  placed  over  a 
smaller  one.     By  means 
of  a  bell -jar  with  a  tight- 
fitting    ground     plate, 
evaporation     may     be 
wholly  prevented    from 
cuttings  or  plants,  if  de- 
sired.   Propagating  beds 

FIG.  96.    Propagating  bed  covered  with  are    often    Covered   With 

glazed  sash.  glazed  sash,  iii  addition 

to  the  glass  roof  of  the  house,  to  assist  in  maintaining  a 
moist  atmosphere  about  the  cuttings  (Fig.  96). 

For  convenience,  we  separate  propagation  by  cuttings 
into  two  divisions,  viz.,  propagation  by  cuttings  from 
dormant  and  from  active  plants.  The  requirements  of 
these  two  classes  differ  in  some  respects. 

a  —  Propagation  ~by  cuttings  from  dormant  plants. 

370.  The  Time  to  Make  the  Cuttings.     We  have  seen 
that  plant  processes  may  not  be  wholly  suspended  during 


Propagation  by  Cuttings.  201 

the  dormant  period  (177).  This  is  true  not  only  of  the 
plant  as  a  whole,  but  also  of  detached  parts  of  the  plant, 
if  they  are  protected  from  evaporation.  If  cuttings  are 
taken  from  a  plant  in  autumn  and  stored  during  winter 
in  a  moist  place  of  moderate  temperature,  the  cut  sur- 
faces will  partially  callus  over  (73),  and  the  formation, 
of  roots  or  buds  may  commence  before  spring. 

When  new  growing  points  must  be  developed  before 
the  cutting  can  form  a  plant,  as  with  cuttings  of  the  stem 
and  roots  of  many  species,  cuttings  of  dormant  plants  are 
preferably  made  at  the  beginning  of  the  dormant  period, 
i.  e.,  in  autumn,  and  placed  during  winter  under  condi- 
tions favoring  the  formation  of  new  growing  points. 

371.  The  Storage  of  Cuttings.  Cuttings  should  be  stored 
in  a  place  sufficiently  moist  to  prevent  loss  of  water  by 
evaporation,  and  warm  enough  to  favor  moderate  root 
growth.  Cuttings  with  ready-formed  buds  must  be  kept 
cool  enough  to  prevent  growth  of  these.  Boot  growth 
may  proceed  to  some  extent  at  temperatures  too  low  to 
excite  the  buds.  These  conditions  are  usually  fulfilled 
by  covering  the  cuttings  in  damp  sawdust,  sand  or  loose 
loam,  and  storing  them  through  the  winter  in  a  moist, 
moderately  cool  cellar,  or  by  burying  them  in  the  open 
ground  beneath  the  frost  line.  In  mild  climates  the  latter 
plan  is  often  preferable.  Stem  cuttings  (373)  of  plants 
that  do  not  root  freely  from  the  stem  are  frequently 
buried  with  the  proximal  end  (116)  uppermost.  This 
gives  them,  to  some  extent,  the  advantage  of  bottom  heat 
(362  a),  since  the  surface  layers  of  the  soil  are  first 
warmed  by  the  sun  in  spring. 

Cuttings  stored  in  the  ground  over  winter  should  be 

taken  up  and  planted  in  spring  before  the  buds  expand. 
12 


202 


Principles  of  Plant  Culture. 


Cuttings  of  evergreen  plants  should  not  be  buried,  as 
this  would  destroy  the  leaves,  without  which  they  rarely 
form  roots.  Cuttings  of  these  plants  are  usually 
made  in  autumn  and  planted  at  once  in  boxes  of 
sand,  which  are  kept  for  a  time  in  a  light,  cool 
place,  as  a  cool  greenhouse,  until  the  growing 
points  of  the  roots  have  formed,  after  which 
they  are  removed  to  a  warmer  location. 

372.  Planting  Cuttings  in  Autumn.     Stem  cut- 
tings of  the  currant  and  other  hardy  plants,  and 
root   cuttings  (376)  of  the  blackberry,  are 
sometimes   made   as   soon   as  the  wood  is 
mature  in  autumn,  and  planted  at  once  in 
well-drained    loamy  or  sandy  soil  in  the 
open  ground.     Cuttings  thus  treated  often 
commence  to  form  roots  before  winter.  They 
should  be  covered  with  a  little 
earth  and  mulched  with  some 
coarse  litter  on  the  approach 
of  freezing-weather,  and  should 
be  shaded  for  a  time  after  the 
opening  of  spring  (Fig.  64). 
373.  Cuttings  from  Dormant 
Stems  (stem  cuttings)  usually 
form  roots  more  promptly  if 
the  proximal   end  is  cut  off 
shortly  below  a  node   (116). 
(See  Figs.  97,  98  and  99. )    In 
certain  plants,  as  many  of  the 
FIG.  97.   FIG.  98.          FIG.  99.      conifers,    cuttings   root   more 
Fig.  97.  stem  cutting  of  currant,  promptly  when  cut  with  a  heel, 


Fig.  99.  currant  cutting  rooted,  the  wood  of  the  previous  year 
at  the  base.     The  very  short  internodes  at  the  junction 


Propagation  by  Cuttings.  203 

of  the  two  seasons'  growth  appear  to  favor  the  emission 
of  roots.  Some  varieties  of  the  grape  root  more  readily 
when  a  short  section  of  the  parent  branch  is  removed 
with  the  cutting,  forming  a  mallet-  or  T-shaped  cutting 
( mallet  cnUtings ) . 

The  cut  forming  the  distal  end  of  the  cutting  (116)  is 
preferably  made  somewhat  above  a  node,  in  order  that 
the  bud  may  not  lose  an  undue  amount  of  moisture  by 
evaporation  from  the  adjacent  cut  surface. 

Cuttings  of  certain  plants  that  do  not  readily  form 
roots  when  made  in  the  ordinary  way,  may  be  induced 
to  do  so  by  "  ringing ' '  the  branch  from  which  the  cut- 
ting is  to  be  made  (428  d),  just  below  a  node  at  about 
midsummer.  Callus  will  then  form  at  the  upper  edge  of 
the  ring  (80),  and  food  will  be  stored  in  the  stem  imme- 
diately above  it.  In  autumn  the  branch  may  be  severed 
just  below  the  ring  and  a  cutting  made,  of  which  the  base 
shall  include  the  callused  part,  and  which  may  be  treated 
in  the  usual  manner. 

374.  The  Proper  Length  for  Stem  Cuttings  depends  up- 
on the  conditions  under  which  they  are  to  be  grown. 
Cuttings  containing  only  one  bud  often  root  freely  and 
form  vigorous  plants  in  the  propagating  bed,  where  heat 
and  moisture  may  be  readily  controlled.     Such  short 
cuttings,  however,  are  seldom  used  except  when  cutting 
wood  is  scarce.     Cuttings  intended  for  planting  in  the 
open  ground  are  preferably  made  at  least  six  inches  long. 

375.  How  to  Plant  Stem  Cuttings.     The  general  rules 
given  for  the  planting  of  seeds  apply  with  nearly  equal  force 
to  cuttings  of  the  stem  (344) .     Single-bud  cuttings  should 
be  planted  with  the  bud  facing  upward,  and  one-half  to 


204  Principles  of  Plant  Culture. 

three- fourths  inch  deep,  in  order  that  the  developing 
bud  may  readily  reach  the  surface.  Cuttings  of  more 
than  one  bud  may  be  placed  upright  or  at  an  angle,  at 
such  a  depth  that  the  bud  at  the  distal  end  (116)  is  about 
on  a  level  with  the  surface.  In  cuttings  of  shrubby 
plants  desired  to  produce  a  single  stem,  the  central  buds 
should  be  rubbed  off  before  planting,  leaving  but  one  or 
two  buds  at  the  distal  end  (Fig.  97). 

376.  Propagation  from  Cuttings  of  the  Root.  Plants 
that  naturally  sucker  from  the  root  (347)  and  some 
others  may  be  propagated  from  short  pieces  of  the  root 
(root  cuttings').  For  this  purpose  roots  of  about  the 
thickness  of  a  lead- pencil  are  commonly  cut  into  pieces 

one  to  three  inches  long  (Fig. 
100),  as  soon  as  growth  ceases 
in    autumn,   and    packed    in 
FIG.  100.  Root  cutting  of  black-  boxes  with  alternate  layers  of 

berry.    (After  Bailey).  mojst  ^^  Qr  mosg>  The  fcoxes 

are  preferably  stored  in  a  cool  cellar  where  they  may  be 
examined  from  time  to  time  during  winter;  the  sand 
or  moss  should  be  moistened  when  it  appears  dry.  Boot 
cuttings  of  diiferent  varieties  of  the  same  plant  often 
require  different  degrees  of  temperature  to  induce  the 
formation  of  callus  and  buds,  hence  the  boxes  should  be 
frequently  examined,  particularly  toward  spring,  in  order 
that  those  in  which  the  cuttings  are  backward  in  starting 
may  be  placed  in  a  higher  temperature.  Thus  treated, 
root- cuttings  of  many  hardy  plants,  as  the  plum,  rasp- 
berry, blackberry,  juneberry  etc.,  often  form  both  buds 
and  rootlets  by  spring,  so  that  they  may  be  planted 
directly  in  the  open  ground.  Those  of  more  tender  species, 


Propagation  by  Cuttings.  205 

as  the  bouvardia,  geranium  etc. ,  will  not  start  to  the  same 
degree,  unless  placed  in  the  propagating  bed  toward 
spring  and  given  bottom  heat. 

Eoot  cuttings  should  be  planted  shallow,  usually  not 
more  than  one- half  to  three- fourths  inch  deep,  in  order 
that  the  developing  bud  may  soon  reach  the  light;  other- 
wise, as  in  too-deeply-planted  seeds,  the  reserve  food  may 
be  exhausted  before  the  shoot  reaches  the  surface.  When 
planted  in  the  open  ground  (372),  the  soil  should  be 
made  very  fine  and  carefully  pressed  about  the  cuttings; 
if  the  weather  is  warm  and  dry,  shading  (Fig.  64)  and 
watering  will  be  necessary. 

b  —  Propagation  by  cuttings  from  active  plants  (green 
cuttings,  slips). 

377.  Nearly  All  Plants  may  be  Propagated  from  Green 
Cuttings.  A  succulent  cutting  of  nasturtium  *  with  its 
leaves  intact,  and  with  its  proximal  end  immersed  in 
fresh  well-  or  spring- water,  will  for  a  time  absorb  suf- 
ficient of  the  liquid  to  make  good  the  loss  from  transpira- 
tion (75).  So  long  as  the  water  remains  fresh  and  the 
tissues  of  the  stem  are  unobstructed,  the  water  thus 
absorbed  will  answer  the  same  purpose  to  this  cutting  as 
if  it  had  been  absorbed  by  the  roots.  Food  formation 
(59)  will  continue,  and  the  growth  current  (80)  will 
transport  the  prepared  food  from  the  leaves  into  the  stem 
and  in  the  direction  of  the  roots.  No  roots  being  present, 
however,  the  growing  points  of  roots  will  form  at  the 
base  of  the  stem,  and  we  shall  soon  have  a  rooted  cutting. 
Not  all  plants,  however,  root  freely  in  water,  possibly 
owing  to  an  insufficient  supply  of  oxygen  therein. 

*  Tropceolum. 


206  Principles  of  Plant  Culture. 

With  very  few  exceptions,  of  which  the  greenhouse 
sinilax  *  is  one,  cuttings  of  the  succulent  growth  of  the 
stem,  with  a  certain  amount  of  healthy  leaf  surface  in- 
tact, will  develop  roots  in  all  plants,  under  proper  condi- 
tions of  humidity  and  temperature;  hence  propagation 
from  green  cuttings  is  a  very  common  and  expeditious 
method  of  multiplying  plants.  The  healthy  leaf  surface, 
capable  of  preparing  food,  is  a  very  important  part  of  a 
green  cutting,  because  the  stem  is  less  abundantly  sup- 
plied with  reserve  food  during  the  growth  period  than 
during  the  dormant  period  (185). 

Since  the  presence  of  leaf  surface  upon  the  cutting 
greatly  promotes  transpiration  (75),  propagation  from 
green  cuttings  is  scarcely  practicable  in  the  open  air. 
Bottom  heat  (362),  with  a  comparatively  low  air  temper- 
ature, is  especially  important  with  green  cuttings,  in 
order  that  the  food  prepared  in  the  leaves  may  be  de- 
voted to  the  formation  of  roots.  A  small  leaf  surface  on 
the  cutting  is  generally  preferable  to  a  larger  one;  in 
many  plants,  a  portion  of  a  single  leaf  is  sufficient.  The 
leaf  surface  should  in  no  case  be  permitted  to  wilt,  hence 
the  cuttings  should  generally  be  sprinkled  with  water  as 
soon  as  made. 

378.  Especial  Care  is  Necessary  in  Propagating  plants 
from  Green  Cuttings.  In  planting  the  cuttings,  the  ma- 
terial of  the  propagating  bed  should  be  put  in  close  contact 
with  the  stems,  and  no  leaves  of  the  cuttings  should  be 
covered.  Since  roots  cannot  form  without  oxygen,  the 
bed  must  not  be  so  freely  watered  as  to  exclude  all  air. 
Transpiration  should  be  reduced  by  sheltering  the  cut- 

*  Asparagus  meteloides. 


Propagation  %  Cuttings. 


207 


tings  from  the  direct  rays  of  the  sun.  Movable  screens 
used  during  sunshine  only,  are  preferable  to  whitening 
the  glass,  which  causes  too  much  shade  when  the  sun  is 
not  shining. 

Damping  off,  a  much -dreaded  disease  causing  cuttings 
to  rot  at  the  surface  of  the  bed,  is  promoted  by  excessive 
heat,  over- watering,  or  insufficient  light  or  air; 
also  by  decomposing   organic  matter  in  the 

material  of  the  bed. 
Affected  cuttings 
should  be  promptly 
removed  and  the 
trouble  corrected. 

379.  Green    Cut- 
tings should  be  Pot- 


ted as  Soon  as  Roots 

Form,  which  may  be 
detected  by  their 
They  should  first  be 


FIG.  101.  FiG.  102. 

Fig.  101.    Cutting  of  chrysanthemum. 
Fig.  102.    Rooted  cutting  of  coleus.    (Both 
after  Bailey). 

foliage  assuming  a  bright  color, 
placed  in  small  pots,  and  until  they  have  commenced 
growth  in  these,  should  be  treated  precisely  as  before 
they  were  potted. 

Propagation  by  green  cuttings  includes  three  divisions, 
of  which  the  requirements  differ  in  some  respects,  viz., 
propagation  by  cuttings  of  herbaceous  plants,  of  woody 
plants  and  of  the  leaf  or  parts  of  the  leaf  (leaf  cuttings}. 

380.  How  to  Make  Green  Cuttings  of  Herbaceous  Plants. 
In  herbaceous  plants  roots  develop  most  readily  from  the 
younger  and  more  succulent  parts  of  the  stem.  Bend 
the  shoot  near  its  terminus  in  the  form  of  a  U,  and  then 
press  the  parts  together.  If  the  stems  breaks  with  a 
snap,  it  is  in  the  proper  condition  to  root  promptly;  if  it 


208  Principles  of  Plant  Culture. 

bends  without  breaking  it  has  become  too  hard.  Cutting 
below  a  node  (116)  is  not  essential  to  the  formation  of 
roots  in  herbaceous  plants.* 

While  the  propagating  house  or  hotbed  is  necessary  to 
the  extensive  multiplication  of  herbaceous  plants  by 
green  cuttings,  the  amateur  may  readily  propagate  a 
limited  number  of  plants  by  the  so-called  "  saucer  sys- 
tem." The  cuttings  may  be  placed  in  glazed  saucers 
containing  sand  that  should  be  kept  saturated  with  water. 
The  saucers  may  be  set  in  any  warm,  well-lighted  place, 
as  the  window  of  a  living  room.  The  stems  being  in 
this  case  in  contact  with  the  water  in  the  bottom  of  the 
saucer,  the  cuttings  require  less  shading  than  those  in  the 
propagating  bed. 

381.  How  to  Make  Green  Cuttings  of  Woody  Plants.  Cut 
tings  of  woody  plants  are  preferably  made  of  harder 
growths  than  those   best   suited  to  herbaceous  plants. 
They  should  be  selected  from  young  shoots  of  medium 
size  and  from  half-mature  wood,  and  should  generally 
contain  from  two  to  three  nodes,  though  where  the  ma- 
terial for  cuttings  is  scarce,  single  buds  may  be  used  in 
many  plants.     The  base  of  the  cutting  is  preferably  cut 
shortly  below  a  node,  but  this  is  not  essential  in  all  plants. 

In  this  kind  of  propagation  a  mild  bottom  heat  is 
helpful,  though  it  is  sometimes  carried  on  during  the 
summer  months  without  artificial  heat. 

382.  Propagation  by  Leaf   Cuttings.     A  considerable 
number  of  plants,  including  the  bryophylluni,  begonia, 
gesnera  and  others,  readily  develop  growing  points  of 

*  In  a  few  plants,  as  the  dahlia,  the  presence  of  a  dormant  bud  at  the 
crown  is  essential  to  the  development  of  the  stem  the  succeeding  year. 
Cuttings  of  such  plants  should  therefore  be  made  below  a  node,  if  the 
roots  are  desired  for  future  use. 


Propagation  by  Grafting. 


209 


the  stem  and  roots  upon  their  leaves,  a  fact  often  turned 
to  account  in  propagating  these  plants.  Well -matured 
leaves,  with  the  principal  nerves  cut  across  on  the  under 
side,  are  held  in  close  contact  with  the  surface  of  the 
propagating  bed  by  pegging  or  by  light  weights,  or  the 
leaf  may  be  cut  into  pieces,  which  may  be  placed  in  the 
propagating  bed  and  treated  as  ordinary  green  cuttings 
(378). 

The  leaves  of  the  bryophyllum  form  rootlets  and  buds 
from  the  notches  on  their  borders  wherever  these  chance 
to  come  in  contact  with  a  moist  medium. 


FIG.  103.  Leaf  of  begonia  on  surface  of  propagating  bed,  forming 
young  plants.  (After  Bailey). 

b  —  Propagation  by  Grafting. 

383.  Grafting  consists  in  placing  together  two  portions 
of  a  plant  or  of  different  plants,  containing  living  cambium 
(69)  in  such  a  way  that  their  cambium  parts  are  main- 
tained in  intimate  contact.  If  the  operation  is  success- 
ful, growth  will  unite  the  two  parts  (70),  and  plant 
processes  will  go  on  much  as  if  the  parts  had  never  been 
separated.  The  union  usually  takes  place  most  rapidly 
when  the  cambium  cells  are  in  the  state  of  most  rapid 
division,  i.  e.,  when  growth  is  most  vigorous. 


210  Principles  of  Plant  Culture. 

The  more  intimate  the  contact  of  the  cambium  in  the 
parts  brought  together,  and  the  less  injury  their  cells 
sustain  in  adjusting  them,  the  more  likely  are  they  to 
unite. 

The  plant  that  it  is  desired  to  change  by  grafting  is 
called  the  stock,  and  the  part  designed  to  be  united  to  the 
stock  is  called  the  graft,  don  (scion)  or  bud. 

Although  the  tissues  of  two  plants  of  differing  char- 
acter often  unite  in  grafting,  each  of  the  united  parts 
almost  always  retains  its  individual  character.  For  ex- 
ample, if  one  or  more  buds  of  the  Ben  Davis  apple  are 
caused  to  unite  by  grafting  with  the  stem  of  a  Baldwin 
apple,  the  parts  that  grow  thereafter  from  the  Ben  Davis 
buds,  though  nourished  by  sap  that  has  passed  through 
the  Baldwin  roots  and  stem,  with  rare  exceptions,  con- 
tinue to  be  Ben  Davis,  while  the  parts  that  grow  from 
the  Baldwin  stock  continue  to  be  Baldwin.  To  this  fact- 
is  due  the  chief  value  of  grafting,  viz.,  it  enables  us  to 
change  the  character  of  a  plant. 

384.  Objects  of  Grafting.     Grafting  enables  us 

a  —  To  change  a  plant  of  an  undesirable  variety  into 
one  or  more  desirable  ones; 

b  —  To  preserve  and  multiply  plants  of  varieties  that 
cannot  be  preserved  or  multipl  ied  by  growing  them  from 
their  seeds; 

c  —  To  hasten  the  flowering  or  fruiting  of  seedlings 
grown  with  a  view  to  improving  varieties; 

d  —  To  change  the  size  of  trees,  as  to  make  them  more 
dwarf; 

e  —  To  restore  lost  or  defective  branches; 

f — To  adapt  varieties  to  special  soils; 


Propagation  by  Grafting.  211 

g  — To  save  girdled  trees; 

h  —  To  avoid  insect  injury  to  the  trunk  or  root,  as  in 
grafting  the  peach  on  the  plum,  or  the  European  grape 
on  the  American. 

385.  The  Plants  that  Unite  by  Grafting.  Plants  of  dif- 
ferent varieties  of  the  same  species  (21)  almost  always 
unite  by  grafting.  Examples,  the  Ben  Davis  and  Bald- 
win apples,  the  Bartlett  and  Seckel  pears. 

Plants  of  different  species  of  the  same  genus  (21)  often 
unite  by  grafting.  Examples,  the  peach  unites  with  the 
plum,  many  pears  unite  with  the  quince;  the  tomato 
unites  with  the  potato. 

Plants  of  different  genera  in  the  same  family  or  order 
(21)  sometimes  unite  by  grafting.  Examples,  the  chest- 
nut unites  with  the  oak;  the  pear  unites  with  the  thorn. 

The  apparent  resemblance  of  two  plants  of  different 
species  is  not  always  evidence  that  they  will  unite  by 
grafting,  e.  g.,  the  peach  and  apricot,  though  resembling 
each  other  in  many  respects,  do  not  readily  unite  by 
grafting,  but  both  unite  freely  when  worked  upon  the 
plum,  though  the  latter  apparently  differs  from  both  the 
peach  and  apricot  more  than  these  differ  from  each  other. 

Many  plants  unite  freely  when  grafted  in  one  direction, 
that  fail  to  unite  when  worked  in  the  opposite  direction j 
e.  g. ,  many  cultivated  cherries  unite  freely  when  worked 
upon  the  mahaleb  cherry,  while  the  latter  fails  to  unite 
when  worked  upon  any  of  the  cultivated  cherries;  many 
pears  unite  freely  when  grafted  upon  the  quince,  but  the 
quince  does  not  freely  unite  when  worked  upon  the  pear. 
The  only  sure  way  of  determining  what  species  may  be 
united  by  grafting  is  by  trial. 


212  Principles  of  Plant  Culture. 

Three  principal  kinds  of  grafting  are  in  use,  viz.,  cion 
grafting,  budding  and  approach  grafting. 

386.  Cion  Grafting  is  used  in  grafting  on  roots  (root- 
grafting)  and  very  often  in  grafting  on  the  stem,  espe- 
cially on  large  trees.     The  cion  is  a  portion  of  the  dor- 
mant stem,  of  the  variety  it  is  desired  to  propagate.     It 
should  generally  be  of  the  preceding  season' s  growth  and 
should  always  contain  one  or  more  healthy  leaf-buds* 
(132).     Cions  are  usually  cut  in  autumn  or  during  mild 
weather  in  winter  or  early  spring,  and  are  commonly  stored 
until  needed  for  use,  in  a  cool  cellar  packed  in  moist  saw- 
dust, moss  or  leaves.     In  climates  of  severe  winters,  they 
should  always  be  cut  in  autumn.     Cions  should  not  be 
kept  so  moist  as  to  cause  swelling  of  the  buds  or  the  for- 
mation of  callus  (73),  nor  so  dry  as  to  cause  shriveling. 

In  cion  grafting,  the  proximal  end  of  the  ciou  (116) 
is  joined  to  the  distal  end  of  the  stock  in  such  a  way 
that  the  cambium  layers  of  the  two  coincide  in  at  least 
one  place.  Cion  grafting  in  the  open  air  is  usually  most 
successful  when  performed  just  before  or  during  the 
resumption  of  active  growth  in  spring,  and  the  cion  is 
thought  to  unite  more  readily  if  in  a  slightly  more  dor- 
mant condition  than  the  stock,  possibly  owing  to  its  more 
ready  absorption  of  water  when  in  this  state. 

The  joints  made  in  cion  grafting  are  generally  coated 
with  a  thin  layer  of  grafting-wax  to  prevent  evaporation 
and  to  keep  out  water.  Sometimes  the  whole  exposed 
part  of  the  cion  is  waxed. 

387.  To    make   Grafting-Wax   for  cleft-grafting  (392), 
melt  together  four  parts,  by  weight,  of  unbleached  rosin, 

*  Flower-buds  are  occasionally  used,  but  should  be  avoided  except  in 
special  cases. 


Propagation  by  Grafting. 


213 


two  parts  of  beeswax  and  one  part  of  beef  tallow;  pour 
into  water,  and  when  sufficiently  cool,  work  with  the 
hands  until  the  mass  assumes  a  buff  color;  make  into- 


FIG.  104.    FIG.  105.          FIG.  106.     FIG.  107.    FIG.  108.    FIG.  109.     FIG.  110. 

Fig.  104.  Grafting  knife.  This  should  be  of  excellent  steel.  The  curve 
in  the  blade  is  not  essential. 

Fig.  105.  Cion  used  for  whip-,  root-  or  cleft-grafting,  one-fourth  natural 
size. 

Fig.  106.    Seedling  root,  used  in  root-grafting,  one-fourth  natural  size- 

Fig.  107.    Cion  shaped  ready  for  insertion,  reduced  nearly  one-half. 

Fig.  108.    Portion  of  seedling  root,  shaped  to  receive  the  cion. 

Fig.  109.    The  cion  and  portion  of  root,  put  together. 

Fig.  110.    The  same  as  Fig.  109,  wrapped  with  grafting  paper. 


214  Principles  of  Plant  Culture. 

rolls  and  wrap  with  parafined  (waxed)  paper  to  prevent 
the  rolls  from  sticking  together.  Several  other  formulas 
are  in  use. 

For  whip-grafting  (390),  where  waxed  cord,  cloth  or 
paper  is  used,  the  beeswax  may  be  omitted  from  the 
above  formula,  or  one-half  more  tallow  may  be  added. 

388.  Grafting  Cord  is  made  by  soaking  balls  of  com- 
mon wrapping  twine  in  melted  grafting  wax. 

389.  Grafting  Paper  is  made  by  painting  thin  inanilla 
paper  with  melted  grafting-wax.    For  painting,  the  paper 
is  preferably  spread  out  on  a  board  of  the  exact  size  of 
the  sheet;  to  prevent  too  rapid  cooling  of  the  wax  the 
board  should  be  heated.     The  wax  should  be  heated  hot 
enough  to  spread  easily,  but  not  so  hot  that  it  is  absorbed 
by  the  paper.    Thin  muslin  or  calico  is  often  used  instead 
of  paper. 

Grafting  paper  and  grafting  cloth  should  be  stored  in 
a  cool,  moist  place  to  preserve  their  adhesiveness. 

Many  kinds  of  cion  grafting  slightly  differing  in  details 
have  been  described,  but  the  more  important  are  whip- 
grafting,  cleft- grafting  and  side- grafting. 

390.  In  Whip-Grafting  (splice-grafting,  tongue-grafting) 
the  cion  and  stock,  which  should  be  of  about  the  same 
thickness,  are  both  cut  oif  with  a  sloping  cut,  about  an 
inch  long,  after  which  a  tongue  is  formed  on  each  by 
splitting  the  wood  longitudinally  a  short  distance  (Figs. 
107,  108).     The  cion  is  best  cut  behind  a  bud,  as  shown. 

In  joining,  the  tongue  of  the  cion  is  inserted  into  the 
split  of  the  stock,  so  that  the  cambium  line  of  the  cion 
and  stock  (69)  coincide  on  one  edge,  and  the  two  are 
crowded  together  with  considerable  force,  after  which  the 


Prorogation  by  Grafting.  215 

joint  is  wrapped  with  a  narrow  strip  of  grafting  paper 
or  grafting  cloth  (389),  or  wound  with  grafting  cord 
(388).  Sometimes  the  joints  are  simply  tied  with  un- 
waxed  cord. 

Whip-grafting  is  generally  used  when  the  stock  is 
little  if  any  thicker  than  the  cion.  It  is  much  used  by 
nurserymen  in  certain  localities  in  grafting  the  apple  and 
some  other  fruits  upon  roots  (root-grafting  (391)). 

Whip-grafting  is  also  considerably  used  in  some  cli- 
mates of  severe  winters,  in  top-grafting  or  "  top-working ' ? 
apple  trees  in  the  nursery,  in  order  to  give  certain 
slightly-tender  varieties  the  benefit  of  a  specially  hardy 
stock.  This  grafting  is  performed  on  two-  or  three-year- 
old  trees,  that  have  been  grown  from  root  grafts.  The 
trunk  is  cut  off  at  the  height  it  is  desired  to  form  the 
head  of  the  tree,  and  a  ciorf  of  the  variety  to  be  propa- 
gated is  inserted 5  or  several  dons  are  inserted  in  as  many 
branches.  The  latter  method,  while  more  expensive,  has 
the  advantage  of  giving  to  the  top-grafted  trees  the  branch 
formation  of  the  stock,  which  is  sometimes  important. 

As  growth  starts  on  top-grafted  trees,  shoots  that  push 
out  from  the  stock  should  be  rubbed  oif  to  prevent  them 
from  robbing  the  cions  of  nourishment. 

391.  Root  Grafting  is  generally  performed  in  winter 
and  in- doors.  The  stocks  are  small  trees,  grown  one  or 
two  years  from  seed  (seedlings).  These  are  dug  in 
autumn,  and  stored  as  recommended  for  cions  (386). 
When  ready  for  grafting,  the  roots  are  washed  and 
trimmed  by  cutting  off  the  larger  branch  roots,  after 
which  the  stem  is  cut  off  at  the  crown,  and  the  distal 
end  of  the  root  (116)  is  shaped  as  directed  above  (390). 


216  Principles  of  Plant  Culture. 

It  is  then  cut  off  two  or  three  inches  down,  and  the 
remaining  root,  if  sufficiently  thick,  is  shaped  for 
another  stock.  Three  or  four  stocks  are  sometimes  made 
from  a  single  root.  As  a  rule,  the  stocks  should  not  be 
less  than  three- sixteenths  inch  in  diameter,  nor  less  than 
two  inches  long. 

Some  nurserymen  prefer  to  make  but  a  single  stock 
from  one  root  (  u  whole-root "  grafts). 

Different  nurserymen  cut  the  cions  for  root- grafts  from 
two  to  six  inches  long.  In  climates  subject  to  drought 
in  summer  and  severe  freezing  in  winter,  the  longer  cions 


FIG.  111.  Shaping  the  cions  for  rootrgrafting.  A,  making  the  "  long 
cut";  B,  cutting  the  "tongue";  C,  cutting  off  the  cion.  These  positions, 
and  the  movements  they  indicate,  are  adapted  to  rapid  work. 

are  more  satisfactory,  as  they  permit  the  stock  to  be 
covered  to  a  greater  depth,  and  encourage  rooting  from 
the  cion,  which  is  sometimes  regarded  as  an  advantage. 

Boot-grafts  should  be  stored  until  time  for  planting 
out,  as  directed  for  cions  (386). 

392.  Cleft-Grafting  is  generally  employed  when  the 
stock  is  considerably  thicker  than  the  cion.  The  cut-  off 
end  of  the  stock  is  split  across  its  center,  with  a  grafting 
chisel  (Fig.  112),  and  the  proximal  end  of  the  cion  (116), 
which  is  cut  wedge-shaped  and  a  little  thicker  on  one 
edge  than  the  other,  is  so  inserted  into  the  cleft  that  the 


Propagation  by  Grafting. 


217 


cambium  of  the  thicker  edge  of  the  cion  forms  a  line 
with  the  cambium  of  the  stock  (Figs.  113,  114,  115). 
Success  is  promoted  if  the  wedge-shaped  portion  of  the 

bud  on  its  thicker  edge.     When 
an  inch  in  thickness,  two  cions 
serted  (Fig.  114),  to  increase  the 
cess.    The  elasticity  of  the  stock 
ficient  pressure  to  maintain  very 
close  contact  between  it  and  the 
cion;    otherwise    it    should    be 
tightly  bound  with  cord  or  raffia 
(393).     The   cions 
should  contain  at  least 
one  bud   beyond   the 
end  of  the  stock.  The 


cion  contains  a 
the  stock  exceeds 
are  usually  in 
chances  of  sue 
should  exert  suf 


FIG.  112.  •  Grafting 
chisel  for  making  the 
cleft  in  cleftrgrafting. 
The  point  at  the  right 
is  for  holdi  ng  the  cleft 
open  during  insertion 
of  cions.  The  projec- 
tion above  is  for  driv- 
ing this  point  in  or 
out;  one-fifth  natural 
size. 


FIG.  113.       FIG.  114.  FIG.  115. 

Fig.  113.  Cion  shaped  ready  for  insertion  in 
cleft  (After  Bailey). 

Fig.  114.  Cions  inserted  in  cleft,  ready  for  waxing. 

Fig.  115.  Cross-section  of  Fig.  113  (After  May- 
nard).  C,  cambium  layer  of  stock;  C',  cambium 
layer  of  cion.  The  cambium  layers  of  the  outer 
edge  of  the  cion  should  form  a  continuous  line 
with  that  of  the  stock.  The  cion  is  made  a  little 
thinner  at  its  inner  edge  to  permit  the  pressure  of 


the  stock  to  be  exerted  at  the  outer  edge. 

wedge-shaped  cut  is  usually  made  about  one  inch  long, 
and  the  cion  should  be  inserted  into  the  cleft  as  far  as 
the  length  of  the  wedge,  after  which  all  the  exposed 
wounded  surfaces,  including  the  distal  end  of  the  cion, 

should  be  coated  with  grafting- wax  (387). 
13 


218 


Principles  of  Plant  Culture. 


Cleft-grafting  is  most  used  in  top-grafting  old  trees. 
Four  to  six  of  the  main  branches,  located  as  nearly  eqi- 
distant  as  possible  (Fig.  116),  are  selected  for  grafting, 
and  it  is  desirable  to  graft  these  rather  near  to  the  top  of 
the  trunk. 

Branches  exceeding  three  inches  in  diameter  should 
not,  as  a  rule,  be  grafted.  About  half  of  the  top  of  the 
tree  should  be  cut  away  just  before  the  grafting,  leaving 
some  branches  to  utilize  a  part  of  the  sap.  The  more  or 
less  horizontal  branches  should  generally  be  selected  for 
grafting,  and  in  these,  the  cleft 
,  .^ —  should  be  made  horizontally,  to 
give  the  two  cions  inserted  an  equal 


FIG.  117.  Cleft-graft  in  trunk 
of  old  grape  vine.  The  cions  are 
usually  inserted  below  the  sur- 
face of  the  ground  in  grafting 
the  grape,  and  110  wax  is  used 
(After  Bailey). 

If  both  the  cions  in  a  branch 


FIG.  116.  Branches  of  tree 
to  be  top-grafted,  as  seen 
from  above,  showing  where 
to  insert  the  cions  to  make  a 
well-formed  head,  i.  e.,  at  the 
dotted  lines. 

opportunity  for  growth 

grow,  the  weaker  one  should  be  pruned  off  later.     As 

growth  starts,  shoots  from  the  stock  must  be  rubbed  off 

(390). 

The  spring  following  the  top-grafting,  all  or  a  part  of 
the  branches  left  on  the  stock  at  grafting  should  be 
pruned  off  to  encourage  growth  of  the  grafts.  If  the 
tree  is  large  and  of  a  vigorous  variety,  it  is  wise  to  leave 
a  part  of  these  branches  until  the  second  spring. 


H  hi/  Grafting.  219 

393.  Side-grafting  is  chiefly  practiced  with  plants  in 
leaf,  under  glass.  The  cion  is  joined  at  the  side  of  the 
stock,  which  is  usually  not  cut  off,  and  is  secured  in 
place  by  wrapping  tightly  with  bast  *  or  raffia.  Three 
slightly  different  methods  are  in  use. 

a  —  A  shaving  of  bark,  thick  enough  to  reach  into  the 
cambium  layer,  is  removed  from  the  side  of  the  stock  by 
making  a  long  vertical  cut  and  a  short  transverse  cut  at 
the  base,  and  to  this  cut  surface  the  cion  is  carefully 
fitted,  and  bound  with  raffia.  This  method  is  called 
veneer-grafting. 

b  —  A  sloping  cut  is  made  rather  deeply  into  the  sap- 
wood  of  the  stock,  into  which  the  cion,  after  being  tapered 
at  its  base  to  the  form  of  a  wedge,  is  in- 
serted (Fig.  118),  and  the  parts  are  then 
held  closely  together  by  binding  with  raffia. 
This  method  is  generally  employed  in  herb- 
aceous grafting,  as  with  the  potato,  tomato 
etc.  It  is  also  much  used  in  grafting  ever- 
greens under  glass,  and  occasionally  in  graft- 
ing outdoor  nursery  trees.  In  the  latter 
case,  a  coating  of  grafting  wax  is  usually 
graft  inserted,  substituted  for  the  tying. 

r  tying.  c  —  ^  short,  transverse  incision  is  made, 
and  immediately  below  this,  a  somewhat  longer,  vertical 
cut  —  the  two  cuts,  which  are  just  deep  enough  to  reach 
through  the  bark,  forming  a  T  (Fig.  121).  The  cion  is 
then  cut  off  with  a  long,  sloping  cut,  and  the  point  in- 
serted, the  cut  surface  inward,  beneath  the  two  lips  of 

*  Bast  is  the  fibrous  inner  bark  of  the  bass-wood  or  linden  tree  (Tilia). 
It  was  formerly  much  used  for  tying  grafts  and  buds,  but  has  been  largely 
supplanted  by  raffia,  which  comes  from  a  palm  of  the  genus  Raphia. 
Rama  may  be  purchased  of  dealers  in  nursery  supplies. 


220 


Principles  of  Plant  Culture. 


bark  formed  by  the  T-  cut,  after  which  the  cion  is  crowded 
downward  until  its  cut  surface  is  in  contact  with  the  cam- 
bium layer  of  the  stock,  when  the  juncture  is  bound  with 
raffia. 

394.     Budding  is  now  extensively  employed  in 
propagating  fruit  trees,  roses  and  the  varieties  of 
deciduous  ornamental  trees  and  shrubs.     A  (usu- 
ally dormant)  leaf-bud,  with  a  small  portion  of 
surrounding  bark  (Fig.  120),  is 
placed  in  contact  with  the  cam- 
bium  layer  of  the   stock. 
Budding  may  be  successful 
whenever  the  cells  of  the 
cambium    layer   are   in   a 
state  of  active  division,  as 
indicated  by  the  ready  sep- 
aration of  the  bark  from 
the  wood.     In  cli- 
mates   having    se- 
vere winters,  bud- 
ding is  most  satis- 
factory when  per- 
formed near  the  end 
v         of  the  growing  sea- 
FIG.  119.         FIG.  121.          FIG.  122.    FIG.  120.    son  and  with  fully - 

Fig.  119.    Shoot  containing   buds.     The   white    ,,-,^,,^1    Km]s     \n 
spaces  about  the  buds  indicate  the  amount  of  bark   i 

to  be  cut  off  with  the  bud.  The  shoot  is  inverted  order  that  the  buds 
for  cutting  the  buds.  ,  , 

Fig.  120.    Bud  cut  off,  ready  for  insertion.  may    not     expand 

Fig.  121.    Bud   partially  inserted   between  the   un^j|  ^ne  followill«v 
lips  of  the  stock. 

Fig.122.  Bud  inserted  and  tied.  (All  after  Bailey).    Spring;     thllS    the 

shoots  growing  from  the  inserted  bud  will  have  the  whole 
season  for  growth  and  maturity. 

With  plants  that  unite  freely  and  with  the  stock  in  the 
proper  condition, 


Propagation  by  Grafting.  221 

395.  Success  in  Budding  Depends  Upon 

a  —  A  fresh  condition  of  the  buds;  these  must  not  be  in 
the  least  shriveled  from  dry  ness. 

b  —  The  proper  removal  and  insertion  of  the  bud;  the 
growing  point  of  the  latter  (67)  must  not  be  injured. 
If  this  comes  out,  leaving  the  bud- scales  partially  hollow, 
the  bud  will  not  grow,  even  if  properly  inserted.  The 
bud  should  be  inserted  promptly  to  avoid  loss  of  moisture. 

c  —  The  proper  wrapping  of  the  wounded  baric,  to  prevent 
evaporation  and  exclude  moisture.  The  ligature  should 
not  cover  the  bud. 

d  —  The  removal  of  the  ligature  after  the  union,  to  per- 
mit expansion  of  the  stock. 

e  —  The  cutting  off  of  the  stock  just  beyond  the  bud,  when 
the  latter  commences  growth,  to  stimulate  its  develop- 
ment. 

Two  methods  of  budding  are  in  use,  viz.,  T-  or  shield- 
budding  and  ring-  or  annular -budding. 

396.  In  T-  Budding,  which  is  the  more  common  and  ex- 
peditious method,  a  short  shaving,  containing  a  hard  and 
plump  bud,  cut  deep  enough  to  reach  through  the  cam- 
bium (Fig.  120),  is  inserted  beneath  the  bark  of  thecion, 
as  described  for  side-grafting  (393  c). 

The  buds,  which  should  be  pluinp  and  mature  and  of 
the  variety  it  is  desired  to  propagate,  are  taken  from 
shoots  of  the  current  season's  growth.  These  shoots 
("bud  sticks")  (Fig.  119)  should  be  cut  the  day  the 
buds  are  to  be  inserted,  and  should  be  trimmed  at  once, 
and  rolled  in  damp  cloth,  to  prevent  loss  of  moisture. 
The  trimming  consists  in  cutting  off  the  leaves,  saving  a 
bit  of  the  leaf  stem  to  serve  as  a  handle  while  inserting 


222  Principles  of  Plant  Culture. 

the  buds.  The  stocks,  whether  grown  from  seeds  or  from 
cuttings,  are  usually  of  one  or  two  season's  growth.  The 
lower  branches  of  the  stock  are  cut  off  up  to  three  inches 
or  more  from  the  ground,  and  a  smooth  place  is  selected 
for  the  bud,  usually  on  the  side  least  exposed  to  the  sun's 
rays.  With  the  budding  knife,  a  T-  shaped  cut  is  made 
on  the  stock  (393  c)  about  two  inches  above  the  ground. 


FIG.  123.  A  lesson  in  budding.  The  left-hand  student  is  cutting  a  bud; 
the  central  one  is  lifting  the  lips  of  the  bark  with  the  spatula  of  his  bud- 
ding knife;  the  right-hand  student  is  tying  the  bud. 

A  bud  is  then  cut  from  the  bud  stick,  by  inserting  the 
blade  of  the  budding  knife  about  a  fourth  of  an  inch 
below  the  bud,  at  such  an  angle  that  the  back  of  the 
blade  nearly  touches  the  bark  of  the  stock.  The  blade 
is  passed  just  behind  the  bud,  touching  the  wood,  bat 
not  removing  much  of  it,  and  then  turned  a  little,  run- 
ning out  about  a  fourth  of  an  inch  above  the  bud  (Fig. 
120,  p.  220).  Often  the  knife  does  not  run  out,  but  the 
bark  is  cut  off  square,  a  quarter  of  an  inch  above  the 
bud,  as  indicated  in  Fig.  119. 

With  the  spatula  of  the  budding  knife  (397),  the  lips 
of  bark  in  the  angles  of  the  T-cut  are  loosened  from  the 


Propagation  by  Gmjtiny. 


223 


wood,  when  the  bit  of  bark  bearing  the  bud  is  slipped 
down  behind  them  (Fig.  121),  with  the  bud  pointing  up- 
ward, until  the  top  end  of  the  bit  of  bark  is  just  below 
the  horizontal  cut  of  the  T.  Some  budders  do  not  use 
the  spatula,  but  raise  the  lips  of  bark  with  the  blade  of 
the  budding  knife.  The  center  of  a  strip  of  moistened 
raffia  is  then  applied  to  the  stock  just  below  the  inserted 
bud  5  the  ends  of  the  strip  are  crossed  on  the  opposite 
side  of  the  stock,  brought  forward  and  again  crossed  just 
above  the  bud,  thus  covering  the  horizontal  cut  of  the  T. 
The  ends  of  the  raffia  are  then  brought 
behind  the  stock,  tied  in  a  half  knot,  11  /  / 

and  drawn  moderately  tight  (Fig.  122), 
pressing  the  lips  down  snugly  about 


;  *"r"~ ' 


FIG.  124.  FIG.  125.      FIG.  126. 

Man  budding  in  nursery  row  (After  Bailey). 
Budding  knife  with  ivory  spatula  on  the  end  opposite  the 

Budding  knife  made  from  erasing  knife  by  rounding  the 


Fig.  124. 

Fig.  125. 
blade. 

Fig.  126. 
edge  at  A. 

the  bud,  which  now  protrudes  between  the  lips. 

If  the  bud  i  1  takes,  7  '  it  will  unite  with  the  stock  in  a 
few  days.  The  raffia  should  be  taken  off  in  about  ten 
days,  by  cutting  it  on  the  back  side  of  the  stock,  to  en- 
able the  latter  to  expand  by  growth. 


224 


Principles  of  Plant  Culture. 


397.  The  Budding  Knife  should  contain  a  blade  of  good 
steel,  shaped  as  indicated  in  Fig.  125,  a,iid  a  round-edged 
spatula  for  lifting  the  bark.    The  spatula  is  better  placed 
on  the  back  of  the  blade,  as  shown  in  Fig.  126. 

398.  Ring  Budding  is  used  to  some  extent  in  the  propa- 
gation of  thick-barked  plants,  as  the  hickory  and  mag- 
nolia.    A  section  of  bark  is  removed  nearly  or  entirely 
around  the  stock,  and  a  similar  section  containing  a  bud 
from  the  variety  it  is  desired  to  propagate,  is  fitted  to  its 
place  and  snugly  bound  with  raffia.     Eing  budding  is 
oftener  performed  in  spring  than  later  in  the  season. 

399.  Approach  Grafting  is  now  seldom 
employed,  except  in  a  few  plants  that 
unite  poorly  by  other  methods.  It  is 
only  possible  between  two  plants  in 


FIG.  127.  FIG.  128. 

Fig.  127.  Two  plants  prepared  for  approach  grafting.  The  cut  surfaces 
a  a,  are  to  be  placed  together  and  bound. 

Fig.  128.  Two  plants  bound  together  for  approach  grafting  (After 
Bailey). 

close  proximity,  or  between  parts  of  the  same  plant,  since 
the  graft  is  not   severed   from  the  parent  until  it  has 


Propagation  by  Grafting.  225 

united  with  the  stock.  The  plants  are  nourished  by  their 
own  roots  until  the  union  takes  place. 

Approach  grafting  is  performed  during  or  just  previ- 
ous to  the  growing  season.  The  parts  are  held  in  con- 
tact by  binding  them  with  raffia;  the  juncture  should 
also  be  waxed  if  the  work  is  done  in  the  open  air. 

Two  methods  of  approach  grafting  are  in  use: 

a  —  A,  shaving  reaching  into  the  cambium  layer  is  re- 
moved from  both  stock  and  graft  on  the  sides  toward 
each  other  (Fig.  127),  and  the  cut  surfaces  are  brought 
together  and  closely  bound  until  they  unite  (Fig.  128), 
after  which  the  graft  is  cut  off  below,  and  the  stock 
above,  the  union. 

b  —  The  top  of  the  stock  is  cut  oif  with  a  long  sloping 
cut,  preferably  behind  a  bud,  and  the  cut  surface  of 
the  remaining  part  is  inserted  beneath  the  bark  of  the 
graft,  as  described  in  side-grafting  (393  c),  except  that 
the  T-cut  is  inverted,  and  the  stock  is  inserted  from  be- 
neath. 

The  graft  is  cut  off  below  the  point  of  union  when  the 
parts  are  fully  united. 

In  both  these  methods  the  graft  should  be  severed 
gradually  to  avoid  a  check  to  the  growth. 

SECTION  II.     TRANSPLANTING 

400.  Transplanting  consists  in  lifting  a  plant  from  the 
medium  in  which  its  roots  are  established,  and  in  re- 
planting the  latter  in  a  different  location.  Transplanting 
is  a  violent  operation  because  the  younger  roots  with 
their  root-hairs  that  absorb  the  greater  part  of  the  water 
required  by  the  plant  (102)  are,  as  a  rule,-  largely  sacri- 


226  Principles  of  Plant  Culture. 

ficed  in  the  lifting  process.  The  water  supply,  so  vitally 
important  to  the  plant  (63),  is  thus  greatly  curtailed 
until  new  root-hairs  can  be  formed. 

Vigorous  plants  are  generally  better  able  to  endure 
transplanting  than  feebler  ones,  because  they  can  sooner 
repair  the  damage  done  to  their  roots.  It  follows  that 
plants  endure  transplanting  with  less  facility  as  they 
advance  in  age  beyond  the  period  of  greatest  vigor  (9). 

401.  The  Most  Favorable  Time  for  Transplanting,  in  the 
case  of  plants  that  live  more  than  one  year,  is  during 
the  dormant  period,  because  growth  processes  are  then 
least  active,  and  comparatively  little  water  is  needed. 
In  countries  having  mild  winters,  the  most  favorable 
time  for  transplanting  is  generally  at  the  beginning  of 
the  dormant  period,  provided  this  comes  at  a  moist  sea- 
son of  the  year.  The  roots  will  then  have  time  to  slowly 
callus  over  their  wounds  and  to  form  new  rootlets,  and 
thus  be  prepared  for  active  growth  in  spring.  But  in 
countries  of  severe  winters,  where  the  roots  are  largely 
frozen  in  the  soil  for  two  or  three  months,  and  in  coun- 
tries in  which  the  autumn  is  generally  dry,  spring  is,  as 
a  rule,  the  more  favorable  season  for  transplanting. 

Trees  that  have  been  long  exposed  to  cold,  drying 
winds  and  have  thus  suffered  depletion  of  water  from 
their  buds  and  branches,  are  better  not  lifted  until  the 
buds  begin  to  swell.  This  is  especially  true  of  evergreen 
trees  in  severe  climates.  Being  always  in  leaf  these  re- 
quire more  careful  treatment  than  deciduous  trees. 

We  shall  consider  transplanting  under  three  divisions, 
viz.,  a,  lifting  the  plant;  b,  removing  the  plant;  and  c, 
replanting  the  plant. 


Transplanting.  227 

A  —  LIFTING  THE  PLANT. 

402.  The  object  to  be  attained  in  this  operation  should 
be  to  remove  the  roots  from  the  soil  with  the  least  possi- 
ble damage  consistent  with  reasonable  economy  of  time 
and  labor.     Plants  in  low  vigor  should  receive  especial 
care  in  this  respect.     Very  young  plants,  as  of  tobacco, 
cabbage,  lettuce  etc.,  grown  thickly  in  the  seed-bed,  are 
often  pulled   from  the   soil   with   the   hands.     In  this 
case,  the  soil  of  the  bed  should  first  be  saturated  with 
water,  in  order  that  the  roots  may  be  broken  as  little  as 
possible,  and  may  come  up  .with  more  or  less  adhering 
soil.     It  is  generally  preferable  to  grow  such  plants  in 
drills  rather  than  broadcast.     This  enables  them  to  be 
drawn  from  the  soil  with  less  damage  to  their  roots. 

Trees  and  shrubs  sufficiently  grown  for  their  final 
planting  out  should  be  more  carefully  handled.  If  it  is 
necessary  to  cut  off  the  main  roots,  the  farther  from  the 
trunk  this  is  done,  the  better  for  the  tree,  and  the  spade 
used  should  be  kept  as  sharp  as  possible.  The  roots  should 
not  be  barked,  mangled  or  split  by  the  digging  tools,  as  is  so 
often  done  with  nursery  stock.  When  possible,  one  per- 
son should  lift  on  the  tree  or  shrub,  while  another  re- 
moves the  earth  from  about  the  roots.  Tree- digging 
machines  are  now  much  used  by  the  larger  nurserymen. 

403.  Lifting   Large  Trees.     Trees  considerably  larger 
than  nursery  sizes  are  best  lifted  when  the  ground  is 
frozen  about  their  roots.     A  trench  may  be  dug  about 
the  tree  before  the  ground  freezes,  deep  enough  to  per- 
mit the  severing  of  the  main  roots,  and  a  hole  for  the 
reception  of  the  cylinder  of  earth  left  within  the  trench 
should  also  be  dug  at  the  place  to  which  it  is  desired  to 


228  Principles  of  Plant  Culture. 

remove  the  tree.  This  cylinder  should  be  large  enough 
so  that  the  tree  is  left  with  abundant  roots,  or  as  large 
as  can  be  removed  with  the  apparatus  at  hand.  When 
the  ground  is  frozen  to  the  proper  depth,  the  tree  may 
be  tipped  over  by  means  of  a  rope  and  windlass,  after 
which  the  cylinder  of  earth  enclosing  the  roots  may  be 
pried  up  sufficiently  to  allow  some  low  vehicle  to  be 
placed  beneath  it.  The  branches  are  usually  permitted 
to  drag  upon  the  ground  in  removal,  as  the  wounded 
parts  may  be  cut  off  in  the  severe  pruning  necessary  in 
planting  large  trees  (409c). 

Large  trees  may  be  lifted  or  lowered  to  accommodate 
grading.  A  trench  is  dug  around  the  tree,  leaving  a 
cylinder  of  earth  intact  about  the  roots.  Soil  is  then 
removed  from  beneath  one  side  of  the  cylinder  below 
the  roots  and  a  block  set  under  as  a  fulcrum.  The  top 
of  the  tree  is  then  inclined  toward  the  fulcrum  by  means 
of  a  rope,  until  the  roots  are  lifted  on  the  opposite  side. 
If  the  tree  is  to  be  raised,  soil  is  packed  under  the  eleva- 
ted roots,  after  which  the  top  is  tilted  in  the  opposite 
direction,  until  the  roots  are  lifted  on  the  fulcrum  side, 
when  soil  is  placed  under  as  before.  This  process  is  re- 
peated until  the  tree  has  been  lifted  to  the  desired  height. 
If  the  tree  is  to  be  lowered,  earth  is  removed  at  each 
tilt. 

404.  Sacking  the  Earth-Enclosed  Roots  is  practiced  in 
lifting  and  removing  orange  trees  in  California  and  may 
be  profitably  employed  with  other  evergreens.  A  rather 
deep  trench  is  dug  at  one  side  of  the  tree,  and  from  this 
trench,  the  deeper  roots  are  severed.  The  top  earth  is 
then  removed  down  to  the  first  lateral  roots,  when  all 


Transplanting. 


229 


the  remaining  large  roots  are  severed  at  some  distance 
from  the  trunk.  The  tree  is  next  tilted  to  one  side  and 
a  piece  of  burlap  or  matting  is  drawn  beneath  it,  after 
which  the  matting  is  folded  about  the  earth  cylinder  and 
well  tied.  . 

B  —  REMOVING  THE  PLANT 

Plants  with  their  roots  out  of  the  soil  should  be  care- 
fully protected  from  mechanical  injury,  from  drying  and 
from  freezing.  To  insure  such  protection,  plants  to  be 
transported  any  considerable  distance  should  be  packed. 

405.  Plants  Packed  for  Trans- 
portation should  be  inclosed 
throughout,  and  the  roots  should 
be  in  close  contact  with  some 
moist  material,  preferably  bog 
moss.  Straw  is  often  used  for 
this  purpose  and  answers  well 
for  packing  about  the  trunks 
and  branches  of  trees,  but  it  is 
inferior  to  moss  for  enclosing 
roots,  as  it  is  more  liable  to 
heat  and  does  not  so  well  retain. 

FIG.  129.  Showing  how  plants 
should  be  packed  for  shipping,  moisture. 

Herbaceous  plants,  as  the  strawberry,  cabbage,  sweet 
potato  etc.,  may  be  packed  in  layers  separated  with  moss, 
as  follows:  Over  the  bottom  of  a  box,  the  width  of 
which  is  about  twice  as  long  as  the  plants  to  be  packed, 
and  which  has  slatted  sides,  place  a  thin  layer  of  damp 
(not  wet)  moss,  and  over  this,  place  a  layer  formed  of  a 
double  row  of  the  plants,  with  their  roots  at  the  center, 
overlapping  a  little,  and  the  tops  toward  the  sides  of  the 
box  (Fig.  129).  Then  put  in  another  layer  of  moss  and. 


230  Principles  of  Plant  Culture. 

of  plants,  and  so  on  until  the  box  is  full,  or  the  desired 
quantity  is  packed.  The  thickness  of  the  layers  will 
depend  upon  the  time  of  year,  the  temperature,  the  dis- 
tance to  be  transported  and  the  kind  of  plants.  The 
warmer  the  weather,  the  thinner  should  be  the  layers  of 
plants,  as  a  rule.  When  the  top  of  the  box  is  put  on, 
the  contents  should  be  pressed  sufficiently  to  prevent  the 
plants  from  shaking  out  of  place. 

406.  Puddling  the  Roots  of  Trees,  i.  e.,  dipping  them 
in  a  paste  of  soil  and  water,  is  much  practiced  by  nur- 
serymen and  tends  to  prevent  them  from  drying.     The 
paste  should  be  made  with  rather  light,  loamy  soil  and 
of  the  consistency  of  cream. 

407.  Trees  are  commonly  Bundled  for  Transportation 
to  economize  space.     For  this  purpose,  a  device  resem- 
bling a  sawbuck,  with  the  arms  cushioned  with  burlap 
or   carpeting   is  very  convenient.     The   trees  are   laid 
between  the  arms,  with  the  roots  placed  evenly  at  one 
end.     The  stems  are  then  drawn  snugly  together  with  a 
broad  strap,  after  which  they  are  bound  with  soft  cord 
or  with  young  and  tender  shoots  of  the  osier  willow.* 
After  bundling,  the  space  between  the  roots  should  be 
filled  with  damp  moss,  and  the  whole  mass  of  roots  sur- 
rounded with  the  same  material.     If  the  distance  to  be 
transported  is  short,  the  mossed  roots  may  be  sewed  up  in 
burlap  or  matting  and  the  tops  may  be  tied  up  in  straight 
straw,  or  the  whole  bundle  may  be  enclosed  in  burlap. 
If  the  distance  is  long,  the  bundle  should  be  boxed,  to 
more  effectually  prevent  the  trees  from  damage.     The 
bundles  may  be  packed  very  closely  in  the  box  without 

*  Salix  viminalis. 


Transplanting.  231 

injury, pprovided  they  nowhere  come  in  direct  contact 
with  it.  Boxed  or  bundled  trees,  that  cannot  be  shipped 
at  once,  should  be  stored  in  a  cool,  damp  place. 
j  408.  Unpacking  and  Heeling-ln.  Packed  plants  should 
generally  be  removed  from  their  package  as  soon  as  they 
reach  their  destination.  If  they  cannot  be  replanted 
immediately,  they  should  be 
heeled-in.  This  consists  in  re- 


FIG.  130.  Nursery  trees  heeled-in  to  prevent  drying.  A,  a  short  row  of 
trees  with  only  the  roots  covered.  B,  a  row  with  their  tops  bent  down  and 
covered  with  earth  at  C  (After  Green).  Sometimes  the  whole  tops  are 
covered.  Trees  should  not  be  heeled-in  in  the  bundles. 

moving  them  from  their  bundles  and  temporarily 
planting  their  roots  in  soil  (Fig.  130).  The  roots  should 
be  well  covered,  and  if  at  a  dry  season,  they  should  also 
be  mulched.  To  avoid  mixing  varieties,  a  separate  row 
should  be  made  of  each  sort. 

Nursery  trees  that  cannot  be  packed  for  shipment  at 
the  proper  time,  are  often  lifted  and  heeled  in,  to  retard 
the  starting  of  the  buds. 

C  —  REPLANTING 

409.  Preparation  of  the  Plant,  a  —  Washing  the  roots. 
The  " puddled"  roots  of  nursery  trees  (406)  are  some- 
times found  inclosed  at  unpacking  in  a  mass  of  mud  that 
is  so  compact  as  to  largely  exclude  the  air  (Fig.  131). 


232 


Principles  of  Plant  Culture. 


The  roots  of  such  trees  should  be  washed  clean  before 
replanting  (Fig.  132). 

b  —  Trimming  the  roots.     The  roots  of  trees  that  have 
been  broken  or  mangled  in  the  lifting  or  transportation, 
should  be  cut  back  to  sound  wood 
with  a  sharp  knife. 

Fibrous  rooted  plants,  as  the  straw- 
berry, are  much  more  readily  planted 
when  the  roots  are  trimmed,  as  shown 
in  Fig.  31,  (p.  73). 

c  —  Reducing  the  top.     The  buds  of 

trees  and  shrubs  should  generally  be 
FIG.  131.       FIG.  132.  ,         ..    .  ,      ,. 

Fig.  131.  Puddled  roots  reduced  in  number  at  replanting  to 

of  nursery  tree.  correspond  with  the  destruction  of 

Fig.  132.     The     same   ,.  ,  ,,       ,.„,. 

washed,  ready  for  plant,  the  younger  roots  during  the  lifting 
ing.  process;   otherwise    the  water   sup- 

plied by  the  roots  may  be  insufficient  to  open  the  buds 
(63).     This  is  best  accomplished  by  thinning  out  and 


FIG.  133. 

Fig.  133.    Boots  of  tree  properly  planted. 

Fig.  134.    Same  improperly  planted. 

cutting  back  the  branches.  As  a  rule,  it  is  better  to  re- 
duce the  top  rather  sparingly  at  replanting,  with  the  ex- 
pectation of  cutting  it  back  further  if  the  buds  do  not 


Tra  nsplanting. 


233 


promptly  open  at  the  proper  time.     The  branches  that 
can  best  be  spared  should  be  removed  (420).     Failure 
to  properly  reduce  the  top  is  a  frequent  cause  of  death 
or  loss  of  vigor  in  transplanted  trees. 
Small  plants  in  leaf,  as  the  strawberry, 
cabbage  etc. ,  usually  endure  transplant- 


FIG.  136. 


FIG.  137. 


Fig.  135.    Strawberry  plant  too  deeply  planted. 
Fig.  136.    The  same  planted  too  shallow. 
Fig.  137.    Strawberry  plant  properly  planted. 

ing  better  if  their  larger  leaves  are  removed  at  replant- 
ing. 

d — Wetting  the  roots  just  before  replanting  is  quite  im- 
portant, as  it  favors  intimate  contact  with  the  soil  particles. 

Plants  that  have  suffered  from  loss  of  moisture  in 
transit  should  have  their  roots  soaked  in  clean  water  for 
a  few  hours  before  replanting.  Deciduous  trees  of  which 
the  bark  is  considerably  shriveled  may  often  be  saved,  if 
the  center  of  the  buds  is  still  fresh,  by  burying  them  in 
moist  earth  until  the  bark  resumes  its  plumpness. 

410.  Replanting  the  Roots.  The  object  to  be  attained 
in  this  operation  is  to  place  moist  and  well- aerated  soil  in 
contact  with  all  of  the  roots  of  the  plant.  The  roots  should 
also  be  placed  at  about  the  same  depth,  and  in  nearly  the 

same  position  that  they  grew  before  the  removal. 
14 


234 


Principles  of  Plant  Culture. 


Fig.  133  shows  the  roots  of  a  tree  properly  planted. 
The  hole  was  dug  sufficiently  large  so  that  the  roots  were 
readily  placed  in  it  without  crowding,  and  the  soil  was 
so  well  worked  in  among  the  roots  that  it  conies  in  con- 
tact with  their  whole  surface. 

Fig.  134  shows  the  roots  of  the  same  tree  improperly 
planted.  The  hole  was  dug  so  small  that  the  roots  were 
necessarily  crowded  out  of  their  natural  position,  and 
the  earth  was  thrown  in  so  loosely  that  it  conies  in  con- 
tact with  only  a  part  of  the  root  surface.  Distortion  of 
the  roots  of  trees  and  shrubs  at  planting  may  cause 
injurious  root  galls. 

In  planting  trees  of  which  the 
roots  are  not  already  inclosed  in 
soil  (403),  the  hands  should  be 
freely  used  to  bring  the  soil  in  con- 
tact with  the  whole  root  surface, 
and  the  earth  should  be  moderately 
packed  about  the  roots  with  the 
feet,  or  otherwise. 

If  the  soil  is  dry,  it  is  probably 
better  to  moisten  it  before  placing 
it  about  the  roots,  rather  than  after, 
as  we  have  then  a  better  opportunity 
to  judge  of  the  quantity  of  water 
required,  and  the  soil  is  less  likely 
to  settle  away  from  the  roots. 

Trees  of  considerable  size 
should  generally  be  staked 
or  otherwise  supported  after 

,       , .  -,     T  •  FIG.  138.    Large  transplanted  tree 

planting,  to  prevent  shaking  woundwlthhayrope  and  supported 
by   wind    (Fig.    138).     Sur-  by  wires, 
rounding  the  trunk  with  poor- conducting  material  as  hay, 
straw  or  canvas,  tends  to  prevent  damage  from  sun-scald 


Transplanting. 


235 


(186),  to  which  recently-  transplanted  trees  are  especially 

liable;  as  the  evaporation  stream  (78)  is  much  reduced, 

the  bark  tends  to  become  unduly  heated. 

411.   Devices  for  Transplanting.     With  young  trees  and 

plants,  that  possess  abundant  vigor,  rapidity  of  planting 

'is  often  of  greater  im- 
portance than  the  ob- 
servance of 
precise  rules. 
In  this  case, 
that  method  is 
best  which  se- 
cures a  given 
number  of 
transpla  n  t  e  d 
and  vigorous- 

1  y-g  r  O  W  1  U  g 


\j 


FIG.  139. 


FIG.  140 


FIG.  141. 


Fig.  139.   Flat  steel  dibber,  (one-sixth  natural  size). 

Fig.  140.    Tool  for  planting  root  grafts  and  cuttings  „!„„+,,     Of    f>»«, 
(much  reduced). 

'  Fig.  141.  Richards'  transplanting  tools,  made  by  F.  least  COSt.  The 
Richards,  Freeport,  N.  Y.  ^  ansplanting 

devices  shown  in  Figs.  139-141,  inclusive,  aid  greatly  in 
accomplishing  this  end. 

The  dibber  (Fig.  139)  is  perhaps,  aside  from  the  spade, 
the  most  valuable  single  tool  for  transplanting.  It  is 
used  for  opening  the  hole  to  receive  the  roots  of  small 
plants,  as  cabbage,  celery,  onions  etc.,  and  for  pressing 
earth  about  the  roots  j  it  answers  equally  well  for  plant- 
ing cuttings  and  root  grafts.  The  manner  of  using  it 
appears  in  Figs.  143  and  144. 

Fig.  140  shows  a  very  convenient  tool  for  planting  root 
grafts  and  cuttings.  It  consists  of  six  steel  dibbers,  at- 
tached in  a  line  to  a  piece  of  scantling,  at  the  distance 


236  Principles  of  Plant  Culture. 

apart  at  which  the  plants  or  cuttings  are  to  be  plantedr 
with  a  handle  affixed  above.  In  using  this  tool,  the  oper- 
ator crowds  the  dibbers  into  the  soil  with  the  foot,  guided 
by  a  line.  He  then  moves  the  frame  to  and  fro  until  the 
holes  are  sufficiently  opened,  when  he  withdraws  the  dib- 
bers by  lifting  the  frame,  and  passes  on  to  repeat  the 
operation.  A  person  follows  inserting  the  grafts  or  cut- 
tings, and  crowding  earth  about  them  with  the  ordinary 
dibber.  See  also  Figs.  145  and  146. 

Fig.  141  shows  a  set  of  transplanting  tools,  useful  in 
removing  a  limited  number  of  plants  that  are  not  closely 

crowded  and  that  need  to  be 
carried  but  a  short  distance. 
They  are  especially  useful  for 
transplanting  strawberry 
plants  during  summer  and 
autumn.  These  tools  and 
also  the  Baldridge  trans- 
planter enable  the  plant  to  be 
readily  lifted  with  a  cylinder 
FIG.  142.  Bemis  Transplanter,  of  earth  and  replanted  in  a 

made  by  Fuller  &  Johnson  Manu-  nole  just  large  enough  to  re- 
facturing  Co.,  Madison,  Wis. 

ceive  the  latter. 

Fig.  142  shows  a  successful  machine  for  planting  to- 
bacco, cabbage,  strawberry  and  other  low,  herbaceous 
plants.  It  plants  these  as  rapidly  as  two  boys  can  de- 
liver them  to  it  in  the  proper  position,  and  waters  the 
soil  about  the  roots  at  the  same  time. 

412.  Potting  and  Shifting.  Potting  is  the  act  of  plant- 
ing plants  in  greenhouse  pots. 

The  pots  should  be  clean  and  are  usually  dipped  in 
water  before  receiving  the  plants,  until  they  have 


Transplanting. 


237 


absorbed  as  much  of  the  liquid  as  they  will  take  without 
leaving  any  upon  the  surface.  Hooted  cuttings  are  gen- 
erally potted  in  pots  one  and  one-half  or  two  inches  in 
diameter,  and  the  plants  are  changed  to  larger  pots 
{shifted)  as  the  roots  require  more  room.  Pots  three 
inches  or  more  in  diameter  are  com- 
monly filled  one- third  full  or  less  with 
pieces  of  broken  pots  (potsherds)  to 


M 
FIG.  143.  FIG.  144. 

Showing  manner  of  using  the  dibber  in  planting. 

Fig.  143.    Inserting  roots  in  the  hole  opened  by  dibber. 
Fig.  144.    Pressing  earth  about  roots  with  the  dibber. 

insure  abundant  drainage,  and  these  are  often  covered  with 
a  little  sphagnum  moss  before  putting  in  the  soil.  The 
soil  used  for  potting  should  be  of  a  sort  that  does  not 
harden,  "bake,"  on  drying,  and  should  generally  be 
liberally  supplied  with  plant  food.  Decayed  sods  from 
an  old  pasture,  leaf  mold,  decomposed  manure,  and  sand, 
the  whole  mixed  and  sifted,  form  a  good  potting  soil. 
The  proportions  of  the  different  ingredients  used  vary 
with  different  plants.  The  soil  should  be  moderately 


238 


Principles  of  Plant  Culture. 


moist,   and  should  be  closely  pressed  about  the  roots. 
The  details  of  potting  are  shown  in  Figs.  147  to  150. 

Shifting  is  the  changing  of  a  plant  from  one  pot  to 
another,  usually  a  larger  one.  Plants  in  small  pots  are 
generally  shifted  as  often  as  their  roots  begin  to  crowd, 
and  the  shifting  is  continued  as  long  as  further  growth  is 
expected.  When  bloom  is  desired,  the  pots  are  permit- 
ted to  become  filled  with  roots  (136). 


FIG.  145.  FIG.  146. 

Rapid  method  of  planting  strawberry  plants  with  spade. 
Fig.  145.    One  man  opens  the  hole  by  inserting  the  spade,  back  side 
forward,  arid  crowding  it  toward  him.    The  other  inserts  the  plant,  taking 
care  to  spread  out  the  roots  well. 

Fig.  146.  The  man  withdraws  the  spade  and  crowds  the  earth  closely 
about  the  roots  of  the  plant  with  his  foot. 

The  pots  into  which  plants  are  to  be  shifted  should  be 
prepared  as  directed  for  potting.  A  little  potting  soil  is 
placed  in  the  bottom  of  the  pot,  or  over  the  drainage 
material,  after  which  the  plant  to  be  shifted  is  tipped 
out  of  its  pot,  by  inverting  the  latter,  placing  the  hand 
upon  the  surface  of  the  soil,  to  support  it,  and  tapping 


Transplanting. 


239 


the  riin  of  the  pot  gently  upon  the  edge  of  the  potting 
bench. 

If  the  soil  is  in  proper  condition,  it  will  readily  slip 
out  of  the  pot  intact,  after  which  it  should  be  placed  in 
the  center  of  the  new  pot  and  the  space  about  it  filled 
with  potting  soil  moderately  pressed  down.  The  roots 
of  woody  plants  should  not  be  covered  deeper  than  they 
grew  before  the  shifting.  See  Figs.  152,  153  and  154. 


FIG.  147.  FIG.  148. 

Fig.  147.  The  workman  takes  a  pot  in  his  left  hand,  and  at  the  same 
time  a  handful  of  potting  soil  in  the  right  hand. 

Fig.  148.  He  places  the  soil  in  the  pot,  pressing  it  against  one  side  with 
the  right  hand,  while  he  picks  up  a  plant  with  the  left  hand. 

D  —  AFTER-CARE  OF  TRANSPLANTED  STOCK 
413.  Mulching  the  soil  about  transplanted  plants  (233) 
is  very  important  in  localities  subject  to  drought.  As  a 
rule,  it  is  wise  to  apply  the  mulch  immediately  after 
transplanting,  but  with  trees  transplanted  very  early  in 
spring,  it  is  better  to  defer  mulching  until  the  soil 
becomes  sufficiently  warm  to  promote  root  absorption 
(102). 


240 


Principles  of  Plant  Culture. 


Watering  recently-transplanted  plants  requires  discre- 
tion. As  a  rule,  mulching  is  preferable  to  watering,  but 
if  mulching  proves  insufficient,  watering  is  the  last 
resort.  In  this  case,  the  soil  about  the  roots  should  be 
saturated  with  water  and  should  not  be  permitted  to 
become  dry  again  until  growth  starts.  A  hole  may  be  made 
in  the  soil  about  the  roots  and  kept  filled  with  water  until 
the  liquid  ceases  to  soak  away  rapidly,  after  which  it 
should  be  occasionally  filled  until  growth  commences. 


_  D_ 


FIG.  149.  FIG.  150. 

Fig.  149.  Placing  the  roots  of  the  plant  against  the  soil  in  the  pot  \vith 
the  left  hand,  he  takes  another  handful  of  soil  with  the  right  hand. 

Fig.  150.  He  fills  the  remaining  space  in  the  pot  with  soil  and  presses 
it  down  with  the  thumbs,  tapping  the  pot  gently  upon  the  bench  in  the 
meantime. 

414.  Shading  plants  transplanted  in  leaf,  until  the  roots 
resume  activity,   is  important  (236).     Evergreen  trees 
and  shrubs  may  often  be  shaded  with  barrels  or  boxes,  or 
with  boughs  from  other  evergreen  trees. 

415.  Tardy  Starting  into  Growth  after  transplanting  is 
usually  evidence  that  the  roots  are  not  supplying  suf- 


Transplanting. 


241 


ficient  water.  In  such  cases,  if  other  precautions  have 
been  observed,  it  is  well  to  further  reduce  the  top.  Plants 
in  this  condition  may  sometimes  be  saved 
by  wrapping  the  stem  in  oiled  or  rub- 
ber cloth  to  check  loss  of  moisture,  or 
with  straw  or  moss  which  may  be  wet 
frequently  till  growth  starts. 

The  device  shown  in  Fig.  151  often 
causes  recently  planted  trees  to  start 
growth  that  seem  likely  to  fail  without 
it.  It  consists  of  a  flask  or  bottle  con- 
taining distilled,  or  rain  water,  sup- 
ported a  few  feet  above  the  ground  and 
connected  by  a  rubber  tube  with  the  cut- 
off end  of  a  root,  as  shown.  If  the  in- 
verted flask  is  used,  a  short  tube  B  B 
should  extend  through  the  cork  and  to 
near  the  bottom  of  the  flask,  to  admit 
air. 

Flower-buds  should  generally  be  re- 
FIG.  151.          moved  from  recently-transplanted  plants 

Device  for  starting 
growth  in  trees.  ( 140  ) . 


FIG.  152.  FIG.  153.  FIG.  154. 

Fig.  152.  A  poorly-potted  plant.  No  provision  is  made  for  drainage; 
the  pot  is  filled  to  the  top  with  soil,  leaving  no  space  to  receive  the  water; 
and  the  stem  of  the  plant  is  not  at  the  center  of  the  pot. 

Fig.  153.     A  well-potted  plant.    A,  potsherds;  B,  moss. 

Fig.  154.  A  poorly-shifted  plant.  C,  open  spaces  due  to  insufficient 
pressing  of  the  soil. 


242  Principles  of  Plant  Culture. 

SECTION  III.     PRUNING 

416.  Pruning  is  the  removal  of  a  part  of  a  plant,  in 
order  that  the  remainder  may  better  serve  our  purpose. 

The  parts  of  plants,  being  less  highly  specialized  than 
those  of  animals,  may  be  removed  with  less  damage  to 
the  individual  than  is  possible  with  animals,  except  in 
the  lowest  types. 

The  word  pruning,  as  commonly  used,  applies  chiefly 
to  the  removal  of  parts  of  woody  plants  with  the  knife, 
shears  or  saw,  but  the  operations  denned  below  properly 
come  under  the  same  head. 

a  —  Pinching  is  the  removal  with  the  thumb  and  finger 
of  the  undeveloped  nodes  at  the  terminus  of  growing 
shoots,  in  order  to  check  growth. 

b  —  Trimming  or  dressing,  when  applied  to  young  nur- 
sery stock,  is  the  shortening  of  both  roots  and  stem,  pre- 
paratory to  planting  in  nursery  rows.  The  roots  are 
shortened  to  facilitate  planting,  and  the  stems  are  short- 
ened to  reduce  the  number  of  buds  (409  c). 

c  —  Topping  is  the  removal  of  the  flower  stalk,  as  in 
tobacco,  to  prevent  exhaustion  of  the  plant  by  the  forma- 
tion of  seed. 

d  —  De-tasseling  is  the  removal  of  the  staminate  flowers, 
(tassels)  of  undesirable  plants  of  Indian  corn,  to  prevent 
pollination  from  them  (151). 

e  —  tuckering  is  the  removal  of  shoots  that  start  about 
the  base  of  the  stem,  or  in  the  axils  of  the  leaves,  as  in 
Indian  corn  or  tobacco.  Its  object  is  to  prevent  exhaus- 
tion of  the  plant  by  the  production  of  needless  shoots. 

f — Disbudding  is  the  removal  of  dormant  buds,  to  pre- 
vent the  development  of  undesirable  shoots. 


Pruning.  243 

g  —  Ringing  is  the  removal  of  a  narrow  belt  of  bark 
about  a  branch,  to  obstruct  the  current  of  prepared  food 
(138). 

h  —  Notching  is  the  cutting  of  a  notch  just  above  or 
below  a  bud  or  twig  to  modify  its  growth. 

i  —  Thinning  fruit  is  the  removal  of  a  part  of  the  fruits 
upon  a  plant,  to  permit  the  remaining  ones  to  attain 
larger  size,  and  to  prevent  exhaustion  of  the  plant  by 
excessive  seed  production. 

j  —  Deflowering  or  defruiting  is  the  removal  of  flower- 
buds  or  fruits  to  prevent  exhaustion  of  the  plant  (140). 

k  —  Root  pruning  is  the  shortening  of  the  roots  of  plants 
in  the  soil,  to  check  growth,  or  to  stimulate  the  forma- 
tion of  branch  roots  nearer  the  trunk  (105). 

417.  The   Season   for   Pruning.     The  milder  kinds  of 
pruning,  as  pinching  and  disbudding,  may  be  performed 
whenever  the  necessity  for  them  appears.     But  in  peren- 
nial plants,  severe  pruning,  as  the  removal  of  branches 
of  considerable  size,  is  generally  least  injurious  if  per- 
formed during  the  dormant  period.     As  the  exposure  of 
unhealed  wounds  may  cause  damage  from  drying,  and 
invites  infection  by  injurious  fungi  (321),  severe  pruning 
is  commonly  best  performed  toward  the  end  of  the  dor- 
mant period,  i.  e.,  in  early  spring  because  healing  is  most 
rapid  at  the  beginning  of  the  growing  season  (73).  Prun- 
ing should  not,  however,  be  done  at  a  time  when  sap 
flows  freely  from  wounds,  as  this  tends  to  waste  reserve 
food.     In  plants  subject  to  this,  as  the  maples  and  grape, 
pruning  is  probably  best  performed  just  before  the  sap- 
flowing  period. 

418.  Where  and  How  should  the  Cut  be  Made  in  Pruning? 
Since  the  movement  of  prepared  food  is  from  the  leaves 


244 


Principles  of  Plant  Culture. 


toward  the  root  (80),  it  follows  that  when  a  branch  is  cut 
off  at  some  distance  from  the  member  that  supports  it, 
the  wound  cannot  heal,  unless  there  are  leaves  beyond 
the  wound  to  manufacture  food,  and  thus  make  a  growth 
current  possible  (73).  The  cut  should,  therefore,  be 
made  close  enough  to  the  supporting  member  so  that  it 
can  be  healed  from  the  cambium  of  the  latter.  In  woody 
plants,  there  is  usually  a  more  or  less  distinct  swelling 
about  the  base  of  a  branch  (Fig.  155),  produced  by  the 


FIG.  155.  FIG.  156.  FIG.  157. 

Fig.  155.  Showing  the  proper  place  to  make  the  cut  in  pruning.  A 
wound  made  by  a  cut  on  the  dotted  line  A-B  will  be  promptly  healed.  One 
made  on  the  line  C-D  or  E-F  will  not.  In  Fig.  156  the  lower  branch  was  cut 
off  too  far  from  the  trunk. 

FiG.  156.  Showing  hoiv  to  make  the  cut  in  pruning  large  branches.  The 
upper  cut,  all  made  from  above,  permits  the  branch  to  split  down.  The 
left  cut,  first  made  partly  from  below,  prevents  splitting  down. 

Fig.  157.  Pruning  to  an  outside  or  inside  bud.  Cut  as  in  the  figure,  the 
uppermost  bud  would  form  a  shoot  that  tends  to  vertical.  Cut  on  the 
dotted  line,  the  uppermost  bud  would  form  a  shoot  tending  to  horizontal. 

cambium  of  the  supporting  member  and  just  beyond  this 
swelling,  a  more  or  less  distinct  line  marks  the  point 
where  the  cambium  of  the  branch  and  of  the  supporting 
member  unite.  In  a  healthy  tree,  a  wound  made  by  a 
branch  of  reasonable  size,  cut  off  at  this  line,  will  usually 
heal  promptly,  but  if  the  cut  is  made  much  further  out, 
it  will  not. 


Pruning.  245 

The  cut  should  generally  be  made  at  right  angles  with 
the  branch,  rather  than  parallel  to  the  supporting  mem- 
ber, since  it  is  important  that  the  wound  be  no  larger 
than  is  necessary.  Wounds  so  large  that  they  cannot 
heal  promptly  should  be  painted  with  lead  and  oil  paint 
to  preserve  the  wood. 

419.  llnhealed  Wounds  Introduce  Decay  into  the  heart- 
wood  of  trees.     Since  the  cells  of  the  heartwood  contain 
no  protoplasm  (72)  and  are  always  moist,  they  form  a 
congenial  field  for  certain  destructive  fungi  (321),  that 
having  once  gained  entrance,  sooner  or  later  destroy  the 
heartwood  of  the  whole  trunk,  thus  greatly  weakening 
it  and  preparing  the  way  for  the  final  destruction  of  the 
tree. 

420.  Objects  of  Pruning.      If  intelligently  performed, 
pruning  has  one  of  four  objects  in  view,  viz. : 

a  —  To  change  the  form  of  the  plant,  as  to  outline  or 
density  (formative  pruning}. 

b  —  To  stimulate  development  in  some  special  part,  as  to 
promote  the  growth  of  wood  or  the  formation  of  flower- 
buds  (stimulative  pruning}. 

c  —  To  prevent  some  impending  evil  to  the  plant,  as  to 
arrest  or  exclude  disease  (protective  pruning}. 

d  —  To  hasten  or  retard  maturity  (maturative  pruning). 

A  — FORMATIVE  PRUNING 

This  aims  to  regulate  the  form  of  the  plant  with  refer- 
ence to  outline  QY  density,  or  to  strength  of  stem.  Pruning  for 
outline  includes  pruning  (a)  for  symmetry  or  picturesque- 
ness;  (b)  for  stockiness  or  slenderness. 

421.  Pruning  for  Symmetry  aims  to  develop  in  the  plant 
a  head  that  is  symmetric  with  reference  to  its  trunk. 


246 


Principles  of  Plant  Culture. 


The  general  principle  involved  is  the  suppression  of 
growth  in  all  parts  that  tend  to  grow  beyond  the  lines  of 
symmetry  (Fig.  158).  This  is  best  accomplished  by 
pinching  (416  a)  during  the  growth  period,  thus  econo- 
mizing the  plant's  energy;  but  when  the  pinching  has 
been  neglected,  the  shoots  that  grow  out  of  symmetry 
may  be  cut  back  during  the  dormant  period. 

In  pru  n  i  11  g 
for  symmetry, 
the  plant 
should  gener- 
ally be  encour- 
aged to  develop 
the  form  that 
is  natural  to 
the  particular 
species  or  va- 
riety; e.g.,  the 
American  elm 
tree,*  which 
naturally  d  e- 
velops  an  open, 
somewhat 
spreading  head 
tending  to  be 
b  r  o  a  d  e  s  t  to- 
ward the  top, 
should  not  be  pruned  to  the  same  form  as  the  sugar 
maple  f  that  develops  a  more  roundish  and  compact  head. 
Evergreens  are  sometimes  pruned  to  ideal  forms,  as  in 
topiary  work,  a  practice  that  is  generally  condemned  by 
good  taste. 

*  Ulmus  Americana.  f  Acer  saccharinum. 


FIG.  158.  Pruning  for  symmetry.  The  branches 
growing  beyond  the  ideal  outline,  indicated  by  the 
dotted  line,  should  be  cut  off  at  the  points  indicated. 


Pruning. 


247 


422.  Pruning  for  Picturesqueness  is  seldom  employed. 
It  requires  a  thorough  knowledge  of  pruning  and  of  plant 
growth,  combined  with  the  conceptions  of  the  artist. 

423.  Pruning  for  Stockiness  aims  to  develop  a  low  head 
with  abundant  branching,  and  a  strong  trunk.     It  is  best 

accomplished  by  pinch- 
ing (416  a)    the  upper- 
most growing  points  dur- 
ing the  growth  period, 
and  encouraging    low 
^ — \      branching  on  the  stem. 
X^  \  If  a  spreading  form  is 

/^ ..         ^desired,     the     lower 

f  \      branches    should    be 

pruned  to  outside  buds  (Fig.  157). 


FIG.  159.  Raspberry 
cane  rendered  stocky  by 
pruning. 


Pruning   for   stockiness   is  FIG.  ieo.. Raspberry 
much  practiced  in  the  rasp-    cane  not  Pruned- 
berry  (Figs.  159  and  160)   and  blackberry, 
in  hedges  and  in  many  ornamental  plants.     It  tends 
to    the    production    of   flower-buds,  by   checking 
growth  of  wood  (137). 

424.  Pruning  for  Slenderness  is  seldom  necessary, 
as  a  slender  growth  may  readily  be  produced  by 
close  planting.  It  is  accomplished  by  persistently 
removing  or  cutting  back  the  lower  branches,  and 
permitting  only  a  few  branches  to  develop  near  the  ter 
minus  of  the  stem. 


248  Principles  of  Plant  Culture. 

425.  Pruning  for  Density  applies  either  to  increasing  or 
decreasing  the  density  of  the  head.  In  ornamental  and 
shade  trees,  a  compact  head  is  often  desirable,  while  in 

fruit  trees,  a  head  that  ad- 
mits abundant  light  and  air 
(Fig.  164)  is  important 
(  243  ) .  To  increase  density, 
encourage  lateral  branching 
by  pinching  all  the  more 
FIG.  lei.  showing  how  to  disbud  prominent  terminal  grow- 

shoots    of   some    coniferous    trees,  fag  points    (Fig.   162).       In 
Picking  out  the  terminal  bud  A  in  . 

spring  usually  causes  both  the  ad-  SOUie     COniferOUS     trees,    as 

jacent  lateral  buds  to  develop.  the    Xorway    Spruce,*    dis- 

budding  of  the  terminal  shoots  (Fig.  161)  in  spring  is 
advisable,  and  in  woody  plants  too  tall  for  pinching,  the 

more  prominent 
terminal  growing- 
points  may  be  cut 
back  with  the  pole 
shears  (431), 
causes  the 
head  to  grow  more 
dense. 

In    pruning   to 

form  an  open  head  (Fig.  164), 
it  is  wiser,  as  a  rule,  to  thin  out 
the  smaller  branches  at  some  dis- 
tance from  the  trunk  than  to  re- 
move  large  branches  at  their 

(right-hand  side)  by  persistent  union  with  the  trunk, 
pinching  of  the  terminal  grow-  „        _ 

ing  points.  426.  Pruning  for  Strength. 

a  —  of  the  Trunk.     Trees  and  plants  grown  in  closely- 

*  Picea  excelsa. 


Pruning. 


249 


planted  nursery  rows  often  have  trunks  insufficiently  de- 
veloped to  support  the  head,  when  planted  by  themselves. 
To  remedy  this  defect,  we  promote  the  formation  of  new 
vascular  bundles  (68,  124)  by  inducing  branching,  which 
we  accomplish  by  cutting  back  the  top  in  proportion  to 
the  slenderness  of  the  trunk  (423). 


FIG.  163.    Unpruned  apple  tree,  with  head  too  dense  to  admit  light. 

b  —  of  the  Branches.  Trees  expected  to  support  heavy 
crops  of  fruit,  or  to  endure  high  winds,  should  have 
branches  developed  with  special  reference  to  strength. 
In  such  cases,  several  medium  to  small  branches  are  better 
able  to  endure  the  strain  than  a  few  large  ones  (245  b)r 

and  the  loss  to  the  tree  of  a  small  branch,  should  it  occur,, 
15 


250 


Principles  of  Plant  Culture. 


is  less  serious  than  that  of  a  large  one.  Forming  the 
head  of  fruit  trees  of  three  or  four  main  branches  is  to 
be  discouraged  for  this  reason.  Several  small  branches 
from  a  common  trunk  are  better,  and  these  should  be  en- 


FIG.  164.    Apple  tree  pruned  with  open  bead,  to  admit  abundant  light. 

couraged  to  leave  the  trunk  at  nearly  right  angles  (Fig. 
157).  Forks  in  the  trunk  of  fruit  trees,  dividing  the 
wood  into  two  nearly  equal  parts  are  objectionable,  as 
one  or  the  other  part  is  very  liable  to  split  down  under 
the  weight  of  a  heavy  fruit  crop. 


Pruning. 


251 


Main  branches  inclined  to  split  down  may  sometimes 
be  prevented  from  doing  so,  by  twisting  two  smaller 
branches  together,  to  form  a  connection  between  them 
(Fig.  165).  The  branches  thus  twisted  often  grow  to- 
gether, forming  a  tie  of  great  strength.  A  main  branch 
that  has  actually  commenced  to  split  down  may  often  be 
saved  by  passing  an  iron  bolt  through  it  and  the  re- 
mainder of  the  trunk.  A  bolt  thus  inserted  may  become 
entirely  inclosed  by  later  growth. 
B  —  STIMULATIVE  PRUNING 

This  depends  upon  the  principle  that  the  suppression  of 
growth  in  one  direction  tends  to  stimulate  it  in  others.  Stim- 
ulative pruning  may  be  employed  either  to  stimulate 
growth  of  leaves,  branches  and  roots,  or  of  flower-buds. 
427.  a  —  Pruning  for  Growth  may 
be  performed,  (a)  By  removing  a  part 
of  the  branches,  thus  reducing  the 
number  of  growing  points  and  the 
surface  exposed  to  evaporation. 
Plants  that  are  not  making  satisfac- 
tory growth  through  feeble  root  action,  may 
often  be  invigorated  by  this  treatment,  which 
is  especially  useful  in  trees  recently  trans- 
planted or  weakened  by  overbearing. 

(b)    By    suppressing    reproduction.      When 
growth  is  desired,  it  is  often  advisable  to  pre- 
vent the  development  of  flowers.     Newly 
FIG.  165.    Branches  of  planted   strawberry,    raspberry   and 

fruit  tree  tied  together  by   *  n  i       -u 

a  graft  formed  of  twisted  blackberry  plants  usually  make  bet- 
twigs,  ter  growth  the  first  season  if  the 
flower-buds  are  picked  off.  The  removal  of  flowers  in  the 
potato  plant  tends  to  stimulate  the  growth  of  tubers, 


252  Principles  of  Plant  Culture. 

especially  in  varieties  that  form  seed.  The  removal  of 
flower- buds  from  cuttings  in  the  propagating  bed  encour- 
ages the  formation  of  roots.  Topping  tobacco  and  rhubarb 
plants  (416  c)  causes  the  leaves  to  grow  larger,  and  of 
onion  plants  stimulates  growth  of  the  bulbs.  De-iasseling 
corn  encourages  growth  of  the  ears  (416  d).  Thinning 
fruit  on  plants  that  incline  to  overbear,  causes  the  re- 
maining fruits  to  grow  larger  (416  i,  160). 

428.  b  —  Pruning  for  Flowers  or  Fruit.  Since  checking 
growth  tends  to  stimulate  the  formation  of  flower- buds 
(135  b),  we  encourage  flowering  in  plants  that  incline  to 
luxuriant  growth,  by  pruning  which  tends  to  check 
vigor.  This  may  be  accomplished, 

(a)  By  pinching  the  terminal  buds  during  the  growth 
period,  as  is  often  practiced  upon  tardy-bearing  fruit 
trees  or  upon  seedling  fruit  trees  of  which  it  is  desirable 
to  soon  learn  the  quality  of  the  fruit.     To  be  successful, 
it  must  be  performed  rather  early  in  the  growing  season, 
and  before  the  time  for  the  formation  of  flower- buds. 
The  blossoms  do  not  usually  appear  until  the  season  fol- 
lowing the  pinching. 

With  plants  that  flower  at  the  terminal  growing  points 
of  the  principal  branches,  as  the  spiraeas,  hydrangeas, 
rhododendrons  etc.,  pinching  to  promote  flowering  is 
not  advisable,  as  it  tends  to  reduce  the  size  of  the  flower 
clusters. 

(b)  By  cutting  back   the  new  growth.     Woody   plants 
that  flower  on  stems  more  than   one  year  old,  as  the 
apple,  pear,  currant  etc.,  when  grown  on  rich  or  well 
cultivated  ground,  or  that  have  been  too  severely  pruned, 
often  tend  to  produce  an  excess  of  new  wood  with  a  very 


Pruning.  253 

feeble  development  of  flower-buds.  In  such  cases,  it  is 
advisable  to  equalize  the  growth  by  a  moderate  cutting 
back  of  all  the  young  shoots.  This  must,  however,  be 
done  with  judgment.  If  the  cutting  back  is  too  severe, 
it  will  stimulate  more  wood  growth  rather  than  the  de- 
velopment of  flower- buds. 

(c)  By  root  pruning.     This  checks  growth  by  reducing 
the  number  of  root-tips,  and  thus  cuts  off  a  part  of  the 
water  supply.    It  is  applicable  to  the  same  cases  as  pinch- 
ing, and  is  accomplished  by  cutting  off  the  extremities 
of  the  roots  by  inserting  the  spade  in  a  circle  about  the 
plant,  or  in  the  case  of  trees  of  considerable  size,  by  dig- 
ging a  trench  sufficiently  deep  to  sever  the  lateral  roots. 
The  severity  of  the  root  pruning  advisable  will  depend 
upon  the  vigor  of  the  growth  it  is  desired  to  check. 

(d)  By  obstructing  the  growth  current.     This  is  accom- 
plished by  ringing  (416  g),  by  notching  (416  h)  and  by 
peeling  the  stem  (73). 

When  ringing  is  practiced,  the  width  of  the  belt  of 
bark  removed  should  usually  not  be  so  great  that  the 
wound  cannot  heal  over  the  same  season  by  the  callus 
formed  on  the  upper  edge  of  the  .ring  (80),  and  it  must 
be  made  sufficiently  early  to  give  time  for  healing.  A 
wider  ring  will  sometimes  heal  if  the  ringing  tools  are 
not  inserted  deeper  than  the  cambium  layer  (81).  In 
the  grape  vine,  in  which  ringing  is  often  practiced  to  in- 
crease the  size  and  earliness  of  the  fruit,  the  width  of  the 
belt  removed  is  less  important,  since  the  canes  that  have 
borne  fruit  are  generally  removed  in  the  annual  pruning. 
But  in  fruit  trees,  the  belt  of  bark  removed  should  not 
much  exceed  one-eighth  inch  in  width.  Simply  cutting 


254  Principles  of  Plant  Culture. 

through  the  bark  with  the   pruning  saw  often  accom- 
plishes the  desired  end. 

Notching  above  or  below  a  bud  or  twig  affects  it  much 
as  girdling  affects  the  entire  girdled  member.  Notching 
below  a  bud  or  twig,  therefore,  checks  its  growth,  and  is 
often  followed  by  fruiting  in  that  part. 

Peeling  the  stem  has  sometimes  been  practiced  to  make 
barren  trees  fruitful  (73).  It  is  a  hazardous  operation 
at  best,  and  should  only  be  used  as  a  last  resort.  It  is 
accomplished  by  making  two  cuts  around  the  trunk, 
usually  several  inches  apart,  and  just  through  the  bark, 
with  one  or  more  vertical  cuts  between  them,  after  which 
the  bark  between  the  circular  cuts  is  carefully  peeled 
off.  It  should  only  be  performed  during  a  period  of 
very  rapid  growth,  and  at  a  time  when  the  wood  is  well 
supplied  with  reserve  food,  i.  e.,  some  time  after  the 
tree  has  put  out  leaves.  It  is  most  likely  to  succeed  in 
warm,  dry  weather,  and  when  the  wound  is  not  shaded 
after  peeling 5  otherwise,  injurious  fungi  are  apt  to  infect 
the  ruptured  cells. 

C  —  PROTECTIVE  PRUNING 

429.  Dead  or  Dying  Members  of  a  plant  Should  Be 
Promptly  Removed,  since  they  more  or  less  endanger  its 
well-being.  Dead  branches  of  any  considerable  size  in- 
vite decay  into  the  stem  which  often  results  disastrously 
(419).  Branches  that  are  dying  from  infection  by  a 
fungous  parasite,  as  the  apple  or  pear  blight,  or  the  black 
knot  of  the  plum  (323),  are  especially  dangerous  and 
should  always  be  removed  as  soon  as  discovered. 
Branches  that  tend  to  interfere  with  the  growth  of 
others  already  formed  should  be  checked  by  pinching 


Pruning.  255 

(416  a),  and  those  that  interfere  by  too  close  contact 
should  be  cut  back  in  proportion  to  the  interference. 

Scraping  off  the  dead  bark  scales  from  old  fruit  trees 
tends  to  remove  certain  destructive  insects  or  their 
eggs.  It  should  be  done  during  the  growing  season,  and 
a  short-handled  hoe  or  a  box-scraper  is  convenient  for 
the  work.  Trees  subject  to  sun- scald  should  generally 
not  be  scraped  unless  other  trunk  protection  is  given. 

D  — MATURATIVE  PRUNING 

430.  a  —  Pruning  to  hasten  maturity.     This  is  seldom 
practiced.     In  nursery  trees  that  tend  to  grow  too  late, 
and  are  thus  subject  to  winter  killing,  the  leaves   are 
sometimes  removed  two  or  three  weeks  before  the  time 
when  hard  frosts  are  expected,  to  encourage  ripening  of 
the  wood. 

The  later  tobacco  plants  in  a  plantation  are  usually 
topped  at  the  time  the  main  crop  is  pushing  the  flower 
stalk,  which  causes  their  leaves  to  mature  in  season  to 
be  harvested  with  the  rest  of  the  crop. 

b  —  Pruning  to  retard  maturity,  see  (159). 

431.  The  Principal  Pruning  Implements  are  the  following: 
The  pruning  knife  (Fig.   166)  is  useful  for  removing 

small  woody  shoots.  The  blade  should  be  of  good  steel, 
and  the  point  should  curve  forward  a  little,  to  prevent 
the  edge  from  slipping  oif  the  branch.  The  handle 
should  be  large  to  avoid  blistering  the  hand,  the  base 
of  the  blade  should  be  thick  to  furnish  a  support  for  the 
thumb,  and  the  rivet  should  be  strong  enough  to  sustain 
hard  pressure  upon  the  handle. 

In  using  the  pruning  knife,  the  shoot  to  be  cut  off 
should  generally  be  pressed  with  one  hand  toward  the 


256 


Principles  of  Plant  Culture. 


member  that  supports  it  and  the  blade  should  be  in- 
serted at  the  proximal  side.  Care  is  necessary  to  pre- 
vent the  blade  from  cutting  too  far. 

The  pruning  saw  (Fig.  167)  is  useful  for  cutting  off 
large  limbs.  Two  toothed  edges  are  preferable  to  one, 
as  the  second  edge  tends  to  prevent  " pinching."  It  is 
well  to  have  the  teeth  on  one  edge  point  backward,  as 
this  enables  the  saw  to  cut  either  when  pushed  or  pulled. 
Sometimes  the  blade  is  curved  like  a  sabre,  with  the 
teeth  on  the  concave  edge  pointing  backward.  The 
blade  should  taper  nearly  to  a  point,  to  enable  it  to 
enter  between  crowded  branches. 


FIG. 


FIG. 
FIG. 


Pruning  knife. 
Pruning  shears. 


FIG.  167.    Pruning  saw. 

FIG.  169.    Hedge  shears  (much  reduced). 


The  pruning  shears  (Fig.  168)  may  be  used  for  the  same 
purpose  as  the  pruning  knife,  but  they  cut  less  smoothly, 
and  less  close  to  the  supporting  member.  They  should  be 


Pruning. 


257 


used  with  the  beveled  edge  of  the  blade  in  close  contact 
with  the  supporting  member.  They  are  excellent  for 
cutting  cions  (386),  and  making  cuttings  (358).  The 
form  shown  in  the  figure  is  perhaps  the  best  one  extant. 

The  hedge  shears  (Fig.  169)  are  especially  useful  for 
pruning  hedges. 

The  lever   shears  (Fig.   170)   are  useful  for 
cutting  off  sprouts  about  the  base  of  trees. 

The  pole  shears  (Fig.  171)  are  useful  for 
cutting  back  the 
shoots  of  tall  trees, 
and  for  removing 
sap  sprouts  (224), 
though  for  this 
purpose  they  have 
the  fault  of  the 
pruning  shears  in 
not  cutting  •  suffi- 
ciently close  to  the 
branch.  They 
should  not  be  used 
for  shoots  much  ex- 
ceeding one  -  half 
inch  in  diameter. 

The  raspberry  hook 
(Fig.  172)  is  used 
for  cutting  off  the 
dead  fruiting  canes  of  the  raspberry  and  blackberry. 
The  cutting  part  is  made  of  a  rod  of  good  steel,  five-six- 
teenths inch  in  diameter,  flattened  and  curved  as  shown, 
with  a  moderately  thin  edge  on  the  concave  side  of  the 
curve.  The  handle  should  be  about  three  feet  long. 


FIG.. 170.  FIG.  171.       FIG.  172. 

FIG.  170.    Lever  shears  (much  reduced). 
FIG.  171.     Pole  shears.     The  wire  connects 
with  a  lever  not  shown  in  the  figure. 
FIG.  172.     Raspberry  hook. 


258  Principles  of  Plant  Cnliure. 

The  following  books  are  recommended  for  reading  in 
connection  with  the  preceding  chapter:  The  Xursery 
Book,  Bailey;  Greenhouse  Construction,  Taft;  Barry's 
Fruit  Garden,  Barry;  The  Art  of  Grafting,  Baltet;  The 
Pruning  Book,  Bailey;  How  to  Make  the  Garden  Pay, 
Greiner. 


CHAPTEB'V 
PLANT   BREEDING 

432.  Plants  Have  Improved  Under  Culture.     From  our 
point  of  view,  our  cultivated  varieties  of  plants  are  su- 
perior to  their  wild  prototypes.     The  strawberries  of  our 
gardens   are  larger,  more   productive   and  firmer  than 
those  of  the  fields;  the  cultivated  lettuces  are  more  vigor- 
ous, more  tender  and  milder  in  flavor  than  wild  lettuces; 
and  the  cultivated  cabbages  and  cauliflower  are  greatly 
superior,  in  the  food  products  they  fumis'i,  to  their  pro- 
genitor.    The  superior  qualities  of  long-cultivated  plants, 
as  compared  with  their  wild  parents,  is  conspicuous  when- 
ever the  wild  form  is  known. 

433.  Whence  this  Improvement?     It  probably  results 
from  two  causes,     a  —  In  culture,  the  natural  hindrances 
to  development  are  largely  removed.     Cultivated  plants 
are  less  crowded  by  too-near  neighbors  than  wild  plants, 
and   they  commonly  receive  more   abundant  food   and 
moisture.      They   are,  therefore,  able  to  reach  higher 
stages  of  development  than  is  possible  in  nature,  where 
plants  are  constantly  restricted  by  environment. 

b  —  The  principle  of  selection  has  doubtless  been  more 
or  less  operative  since  the  beginnings  of  culture  (19). 
All  of  our  cultivated  plants  must  have  existed  originally 
in  the  wild  state.  The  most  satisfactory  plants  of  any 
desirable  species  have  been  most  carefully  guarded,  and 
when  the  art  of  propagation  became  known,  these  plants 
were  most  multiplied.  In  each  successive  generation, 

(259) 


260  Principles  of  Plant  Culture. 

the  most  desirable  individual  plants  of  each  species  were 
protected  and  multiplied,  or  at  least  were  permitted  to 
perpetuate  themselves.  Since  the  offspring  tends  to  re- 
semble the  parent  (18),  the  persistent  propagation  from 
the  best  has  resulted  in  more  or  less  marked  improve- 
ment. Chance  crossings  have  aided  the  process  (445). 
These  facts  furnish  hints  for  the  further  improvement  of 
plants.' 

434.  The  Variability  of  plants  Renders  their  Improve- 
ment Possible.     In  a  species  of  which  the  individual 
plants  are  all  practically  alike,  as  in  many  wild  plants, 
we  can  do  little  in  the  way  of  plant  breeding,  except  to 
give  treatment  that  promotes  variability.     In  a  species 
in  which  the  individuals   manifest   different   qualities, 
however,  we  may  hope  to  secure  improvement  by  using 
the  most  desirable  plants  as  parents  from  which  to  secure 
still  further  variability. 

435.  Variations  are  Not  Always  Permanent.     If  we  find 
a  chance  seedling  of  the  wild  blackberry,  for  example, 
that  has  remarkably  fine  fruit,  the  plants  grown  from 
seeds  of  this  fruit  are  not  always  equal  in  quality  to  the 
parent.     The  tendency,  in  such  cases,  is  for  the  seedling 
plants  to  revei*t  or  go  back  to  the  ordinary  type  of  the 
species,  and  the  more  marked  the  variation,  the  stronger 
is  the  tendency  to  reversion. 

436.  How  to  Fix  Desirable  Variations.     A  fixed  varia- 
tion, i.  e. ,  a  variation  of  which  the  progeny  resembles  the 
parent  in  all  important  characters,  becomes  a  variety  (21)* 
as  this  word  is  used  with  reference  to  cultivated  plants. 


*  Varieties   that   reproduce   their  more  important  characters  when 
grown  from  seed,  are  often  called  races. 


Plant  Breeding.  261 

There  are  two  possible  ways  of  fixing  a  desirable  varia- 
tion: 

a  —  By  propagating  the  plant  by  division  (345).  This 
enables  us  to  maintain  a  given  variation  through  many 
generations  with  comparatively  little  deviation  from  the 
form  with  which  we  started  (341).  Our  varieties  of 
fruits,  potatoes,  geraniums  and  many  flowering  plants, 
and  of  many  of  our  finest  ornamental  trees  and  shrubs 
are  fixed  in  this  manner.  It  is  well  known  that  varie- 
ties propagated  in  this  way  rarely  "come  true"  from 
seed,  i.  e.,  their  seed  does  not  usually  produce  plants  of 
the  same  variety  as  the  parent.  But  it  is  not  practicable 
to  propagate  all  plants  by  division. 

With  plants  more  conveniently  propagated  from  seed, 
as  the  cereals,  Indian  corn  and  most  garden  vegetables, 
we  may  fix  varieties  to  a  certain  extent, 

b  —  By  persistent  selection  toward  an  ideal  type.  For  ex- 
ample, if  we  discover  a  single  pea  plant  in  a  row  of  peas 
that  produces  earlier  pods  than  any  other  plant,  and  we 
desire  to  fix  this  variation,  we  would  save  all  the  peas 
from  this  plant  and  sow  them  the  next  spring.  Most  of 
the  plants  from  this  seed  will  probably  be  later  than  the 
parent,  but  two  or  three  of  them  may  equal  it  in  earli- 
ness.  We  would  save  the  seeds  from  the  earliest  plant 
again,  and  continue  this  selection  through  several  sea- 
sons. It  would  be  well  to  note  the  incidental  characters 
of  the  earliest  plants,  i.  e.,  whether  the  pods  are  borne 
singly  or  in  pairs,  if  they  are  straight  or  crooked,  and 
whether  the  plants  are  tall  or  dwarf.  Having  decided 
on  the  characters  that  seem  to  accompany  the  extreme 
earliness,  we  should  save  seeds  only  from  plants  that 


262  Principles  of  Plant  Culture. 

show  all  these  characters.  After  following  this  kind  of 
selection  eight  or  ten  years,  we  may  be  able  to  introduce 
a  new  variety  of  pea. 

It  is  impossible  to  so  fix  variations  in  plants  grown  from 
seed  that  they  will  continue  to  come  true  without  a  cer- 
tain amount  of  selection,  hence  varieties  propagated  by 
seed  continually  tend  to  "run  out,"  i.  e.,  to  lose  their 
distinctive  characters.  Seed  growers  find  it  necessary 
to  use  the  utmost  care  in  maintaining  their  varieties,  and 
the  more  distinct  a  variety  propagated  by  seed,  the  more 
difficult  it  is  to  maintain. 

437.  Seed   Selection   is  of   Great   Importance.     From 
what  has  been  said,  it  is  clear  that  the  cultivator  cannot 
afford  to  be  indifferent  as  to  the  quality  of  the  seed  he 
sows.     It  is  not  enough  that  the  seed  is  fresh  and  plump  5 
it  should  be  of  carefully-bred  varieties.     In  the  cabbage 
and  cauliflower,  success  or  failure  in  the  crop  will  depend 
largely  upon  the  quality  of  seed  sown,  and  the  same  is 
more  or  less  true  in  all  crops  grown  from  seed. 

438.  We  Can  Induce  Variation,  in  some  cases,  by  special 
treatment  of  the  parent  plants,  or  by  the  use  of  a  par- 
ticular selection  of  seed. 

a  —  By  culture.  It  is  generally  conceded  that  culture 
tends  to  promote  variations  that  would  not  have  appeared 
in  the  wild  state,  in  consequence  of  the  changed  growth 
conditions.  In  improving  wild  plants,  therefore,  we 
probably  have  a  better  chance  of  securing  variation  by 
gathering  seeds  from  such  wild  plants  that  have  been 
placed  under  high  cultivation  than  from  those  that  have 
not  been  submitted  to  culture. 

b  —  By  growing  seedlings.  In  plants  habitually  propa- 
gated by  division  (345),  as  the  apple,  potato,  dahlia  etc., 


Plant  Breeding.  263 

we  secure  variation  by  growing  plants  from  seed.  The 
parent  plant,  not  having  been  fixed  by  long  selection,  as 
is  the  case  with  varieties  grown  from  seed,  is  in  a  state  of 
variation,  and  hence  its  progeny  usually  varies  widely. 
From  these  variable  seedlings,  desirable  individuals  may 
be  selected  for  fixing.  Since  most  of  our  varieties  that 
are  propagated  by  division  are  highly  developed,  their 
seedlings  are  usually,  though  not  necessarily,  inferior  to 
the  parents. 

c  —  By  crossing  varieties  or  species.  This  is  the  most 
important  method  of  plant  improvement.  By  procuring 
fecundation  of  the  germ  cell  of  a  plant  of  one  variety 
with  pollen  from  a  plant  of  a  different  variety  or  species 
(150)  through  cross- pollination  (152),  we  obtain  a  vari- 
able progeny  of  which  the  individual  plants  may  be  ex- 
pected to  resemble  both  parents  in  different  degrees.  For 
example,  if  we  secure  fecundation  of  a  number  of  ovules 
of  the  Worden  grape  with  pollen  from  the  Delaware 
grape,  and  plant  the  seeds  from  the  fruits  thus  secured, 
we  may  expect  that  some  of  the  seedlings  will  resemble 
both  parents  about  equally,  that  others  will  chiefly  re- 
semble the  Worden,  but  will  show  a  few  characteristics 
of  the  Delaware,  while  others  again  will  chiefly  resemble 
the  Delaware,  but  will  possess  a  few  characteristics  of  the 
Worden.  It  would  not  be  surprising  if  we  secure  a  vine 
having  the  vigor,  productiveness  and  large  fruit  of  the 
Worden,  with  the  color  and  delicious  flavor  of  the  Dela- 
ware. This  we  may  almost  certainly  accomplish  if  we 
continue  our  trials  a  sufficient  time.  In  other  words,  we 
may  often  combine  the  good  qualities  of  two  varieties  into  a 
single  variety  by  securing  a  number  of  cross-fecundations  be- 


264  Principles  of  Plant  Culture. 

tween  the  two  (440),  and  rearing  plants  from  the  seeds  thus 
formed. 

439.  The  Selection   of  Subjects  for  Crossing.     If  the 
object  of  crossing  is  simply  to  secure  variation,  as  is 
sometimes  the  case  with  wild  fruits,  the  parents  should 
differ  from  each  other  as  widely  as  possible,  provided 
only  that  they  are  capable  of  crossing  freely.     Crosses 
between  allied  species  (hybrids  (23)),  when  this  is  pos- 
sible, will  be  more  likely  to  accomplish  the  object  sought 
than  between  plants  of  the  same  species. 

If  the  object  is  the  improvement  of  present  varieties,  the 
parents  should  be  chosen  with  reference  to  the  qualities 
desired  in  the  new  variety.  For  example,  if  it  is  desired 
to  produce  a  hardy,  late- keeping  apple,  of  first  quality, 
any  hardy  variety  that  keeps  well,  whatever  its  quality, 
may  be  crossed  with  any  other  hardy  apple  of  first  qual- 
ity, whether  it  keeps  poorly  or  well,  though  of  two  ap- 
ples of  first  quality,  the  better  keeper  should  be  chosen. 

The  plant  breeder  should  first  have  a  definite  idea  of 
the  qualities  he  desires  to  secure  in  his  proposed  variety, 
and  should  then  study  with  much  care  the  qualities  of 
the  varieties  that  he  proposes  to  use  as  parents.  The 
two  varieties  that  contain  the  largest  number  of  the  de- 
sired qualities  should  be  chosen. 

440.  Cross-Fecundation  is  accomplished  through  cross- 
pollination  of  the  flowers  (152)  5  i.  e.,  by  placing  pollen 
from  the  anthers  of  a  flower  of  one  of  the  varieties  we 
desire  to  cross  upon  the  stigma  of  the  other  variety. 

441.  Preparing  the  Flower   for   Crossing.     To  prevent 
self-pollination  (152)  in  perfect  flowering  plants  (154), 
we  emasculate  (e-mas'-cu-late)  the  flowers,  i.  e.,  remove 


Plant  Breeding. 


265 


FIG.  173.    Case  of  instruments  and 
sacks  for  crossing  plants. 


the  anthers  (144)  before  the  pollen  is  mature.  Prior  to 
maturity,  the  anthers  are  generally  pale  in  color  and 
nearly  smooth  on  the  surface,  with  no  visible  pollen,  but 
a  little  later,  the  pollen  in  most 
plants  is  visible  as  a  bright  yel- 
low dust  adhering  to 
the  anthers.  The  an- 
thers may  be  picked 
off  with  the  forceps, 
or  the  filaments  that 
support  them  may  be 
clipped  off  with  the 
points  of  the  scissors. 
They  must  generally  be  removed  before  the  petals  open 
(143).  The  latter  may  be  gently  opened  with  the  for- 
ceps or  needle,  or  they  may  be  carefully  removed. 

In  the  flowers  of  certain  plants,  as  the  pea,  wheat  and 

grape,  pollination  takes 
place  before  the  blossom 
opens,  hence  in  these 
plants  it  is  necessary  to 
emasculate  the  flowers 
very  early. 

442.  To  Prevent  Unde- 
sired  Pollination,  the 
blossom  should  be  in- 
closed by  tying  over  it  a 
sack  of  thin  cloth  or  pa- 
per at  the  time  of  re- 
moving the  anthers.  The 
sack  will  of  course  have 
to  be  removed  for  polli- 
nation, after  which  it  should  be  promptly  replaced. 


FIG.  174.  Emasculated  flower  inclosed 
in  sack. 


1(5 


266  Principles  of  Plant  Culture. 

Pollination  should  be  performed  twenty-four  to  forty- 
eight  hours  after  emasculation  (441),  the  period  depend- 
ing upon  the  plant  and  the  stage  of  development  of  the 
flower  at  the  time  of  the  latter  operation  (151).  Applying 
the  pollen  on  two  consecutive  days  tends  to  insure  success. 

The  pollen  is  applied  by  placing  an  anther  (144)  con- 
taining mature  pollen  in  direct  contact  with  the  stigma 
(145),  or  by  removing  some  of  the  pollen  upon  the  back 
of  the  point  of  a  penknife  or  by  means  of  a  camel' s-hair 
brush,  and  carefully  applying  it  to  the  stigma.  A  pin, 
of  which  the  head  has  been  flattened  by  hammering,  in- 
serted in  the  end  of  a  stick,  forms  a  convenient  tool  for 
this  work. 

The  best  time  for  pollination  in  the  open  air,  is  often 
in  the  early  morning,  since  the  atmosphere  is  then  usually 
still,  and  contains  little  pollen  from  other  flowers,  Vhich, 
if  freely  present  in  the  air,  may  vitiate  the  results  of  the 
pollination. 

443.  The  After-Care  of  Crosses.  After  the  last'pollina- 
tion,  the  blossom  should  again  be  inclosed  until  fecunda- 
tion is  effected,  which  is  indicated  by  a  rapid  enlarge- 
ment of  the  ovary.  The  paper  sack  may  then  be  replaced 
by  one  of  mosquito  netting.  This  should  be  securely, 
but  not  too  tightly,  tied  about  the  stem  of  the  pollinated 
flower,  to  protect  the  inclosed  fruit  or  seed-vessel  from 
injury  during  growth  and  maturity,  as  wrell  as  to  render 
it  conspicuous.  A  label  should  be  placed  within  the 
sack,  or  tied  on  with  it,  giving  the  name  of  the  variety 
whence  the  pollen  was  secured.  It  is  also  desirable  to 
record  all  the  operations  and  observations  relative  to  the 
crossing. 


Plant  Breeding.  267 

444.  The  Selection  of  Crossed  Seedlings  is  a  most  im- 
portant operation  in  producing  new  varieties  by  crossing. 
If  none  of  the  seedlings  of  the  first  generation  exhibit 
the  desired  qualities,  those  of  a  succeeding  generation 
may  exhibit  them.  The  plants  nearest  the  ideal  should 
be  selected,  and  all  the  seeds  from  these  preserved  for 
planting.  When  the  ideal  plant  is  found,  it  may  be 
readily  fixed  by  means  of  cuttings  or  grafts  in  plants 
generally  propagated  in  this  way.  In  those  propagated 
by  seed,  several  generations  of  culture  and  selection  may 
be  necessary  before  the  progeny  will  uniformly  resemble 
the  parent. 


FIG.  175.    Diagram  illustrating  the  selection  of  seedlings  from  a  cross. 

The  variations  in  the  seedlings  from  two  crossed  vari- 
eties, and  the  kind  of  selection  needed  to  fix  the  desired 
variation,  are  illustrated  by  the  following  diagram  (Fig. 
175).  Let  a  represent  the  seeds  from  two  crossed  flowers 
A  and  B.  The  plants  from  these  seeds  will  probably  be 
quite  variable,  as  is  indicated  by  the  divergent  lines. 
Let  us  suppose  the  variation  marked  i  to  be  nearest  the 
ideal  form.  The  plants  grown  from  i  will  again  be  quite 
variable  in  the  second  generation  &,  but  probably  less  so 
than  in  the  first  generation.  No  plants  of  the  second 
generation  may  be  nearer  the  ideal  type  than  those  of 
the  first  generation,  but  we  select  the  plant  nearest  to  our 
ideal,  and  plant  the  seeds  from  this.  Each  succeeding 
generation  may  be  expected  to  produce  less  of  variability 


268  Principles  of  Plant  Culture. 

than  the  one  before  it.  By  and  by,  we  may  hope  to  se- 
cure a  form  that  approaches  our  ideal  and  comes  toler- 
ably true  from  seed. 

445.  Planting    with    Reference   to   Chance    Crossings. 

Many  valuable  varieties  have  unquestionably  arisen  from 
accidental  crosses  between  plants  of  different  varieties 
that  chanced  to  be  growing  in  proximity.  Profiting  by 
this  hint,  varieties  are  sometimes  planted  near  together 
to  favor  self -crossing,  a  practice  to  be  encouraged. 

446.  Those  Who  Improve  Plants  are  True  Benefactors. 
He  who  produces  fruits  or  flowers  for  others  works  a 
transient  good.     But  he  who  produces  a  variety  of  fruit 
or  flower  that  is  superior  to  any  now  known  confers  upon 
his  race  a  permanent  good.     Until  the  introduction  of  the 
Wilson  strawberry,  the  markets  of  our  country  were  not 
supplied  with  this  delicious  and  wholesome  fruit,  because 
no  known  variety  was  sufficiently  productive  to  be  gen- 
erally profitable,  or  sufficiently  firm  to  endure  long  car- 
riage.    What  a  blessing  was  conferred  upon  us  by  a 
Mr.  James  Wilson,  of  Albany,  1ST.  Y. !     There  are  wild 
fruits  in  our  copses  to-day  that  are  doubtless  worthy  of 
improvement,  and  in  most  of  our  fruits  now  under  cul- 
ture the  development  of  superior  varieties  would  greatly 
enhance  their  value.      "The  harvest  truly  is  great,  but 
the  laborers  are  few.'7 


The  following  books  are  recommended  for  reading  in 
connection  with  the  preceding  chapter :  Plant  Breeding, 
Bailey;  Variations  of  Animals  and  Plants  Under  Domes- 
tication, Darwin;  Propagation  and  Improvement  of  Cul- 
tivated Plants,  Burbridge;  Origin  of  Cultivated  Plants, 
De  Candolle. 


APPENDIX 


A  SYLLABUS  OF  LABORATORY  WORK 

The  laboratory  exercises  here  outlined  have  been  used 
by  the  author  in  his  instructional  work. 

Each  student  performs  the  exercises,  so  far  as  possible, 
and  the  apparatus  needed  is  provided.  The  student 
should  be  required  to  write  a  description  of  the  work 
performed,  stating  results  in  every  case,  supplementing 
his  notes  by  drawings  in  special  cases. 

It  has  not  been  found  practicable  to  make  the  lecture 
room  and  laboratory  work  fully  correspond  as  to  time, 
but  the  effort  has  been  made  to  do  this  as  far  as  possible. 

A  greenhouse  is  very  desirable  for  this  kind  of  instruc- 
tion, and  if  the  instruction  is  given  in  winter,  a  "garden 
house,"  i.  e.,  a  glass  house  inclosing  an  unobstructed  area 
of  garden  soil  is  scarcely  less  important.  But  in  the  ab- 
sence of  these  conveniences,  a  few  window  boxes  will 
furnish  a  tolerable  substitute. 

When  the  exercises  are  carried  out  during  winter, 
considerable  foresight  is  essential  to  have  the  needed 
materials  in  condition  for  use  at  the  proper  time. 

To  stimulate  observation  (1).*  A  few  object  lessons  are 
given  to  encourage  observation  and  correct  reasoning. 
A  twig,  an  ear  of  corn  or  a  potato  tuber  is  given  to  each 
student  and  all  are  encouraged  to  vie  with  each  other  in 
discovering  new  points,  and  in  discussing  the  reasons 
therefor.  This  lesson  is  frequently  repeated  during  the 
term. 


*The  numbers  in  parenthesis  refer  to  the  paragraphs  in  the  book. 

(269) 


270 


Principles  of  Plant  Culture. 


Cell  structure  (12).  The  students  examine  the  pulp  of 
a  mealy  apple  and  of  a  potato,  and  cross- sections  of  a 
young  bean  plant,  with  simple  lenses  of  rather  high  mag- 
nifying power.  If  a  compound  microscope  is  available, 
many  mounted  objects  illustrating  the  cell  structure  of 
plants  may  also  be  shown. 

Absorption  of  water  by  seeds  (26).  For  the 
exercises  suggested  by  paragraphs  26  and 
27,  a  means  of  weighing  and  of  measuring  the 
volume  of  large  seeds,  as  beans,  with  some 
degree  of  accuracy  is  needed.  The  device 
shown  in  Fig.  176  answers  this  purpose,  and 
one  can  be  provided  for  each  pair  of  stu- 
dents at  a  moderate  cost.  It  consists  of  a 
graduated  glass  cylinder  of  200  cubic  cen- 
timeters capacity  and  a  test  tube  about  6 
inches  long.  For  determining  the  volume, 
the  cylinder  is  partly  filled  with  water  and 
the  height  to  which  the  water  rises  is  noted. 
The  seeds  are  then  dropped  in  and  the  glass 
is  shaken  a  little  to  remove  the  air  bubbles. 
The  height  of  the  water  is  again  noted, 
when  the  difference  in  the  two  readings  in- 
dicates the  volume  of  the  seeds  in  cubic 
centimeters.  For  weighing,  the  empty  test 
tube  is  placed  in  the  cylinder  in  the  posi- 
tion shown  (Fig.  176).  The  height  to 
which  the  water  rises  is  then  noted,  after 
which  the  seeds  are  dropped  into  the  test 
FIG  lie.  Device  tube,  and  the  top  of  the  cylinder  is  jarred 
d°ete?mfninngg  fSe  slightly  by  tapping  it  with  the  pencil, 
volume  of  seeds.  The  height  of  the  water  is  again  noted, 
when  the  difference  in  the  readings  indicates  the  weight 
of  the  seeds  in  grammes. 

The  test  tube  should  float  in  the  center  of  the  cylinder, 
as  shown,  and  the  readings  should  be  taken  with  the  eye 
on  a  level  with  the  surface  of  the  water. 

Each  student  (or  pair  of  students)  is  provided  with 
the  apparatus  shown  in  Fig.  176,  and  with  two  bottles  of 
at  least  100  cc.  capacity,  with  corks.  Each  bottle  should 


Appendix  —  Syllabus  of  Laboratory  WorJf.         271 

have  a  strip  of  white  paper  pasted  vertically  upon  it  to 
receive  the  name  of  the  student  and  other  data. 

Kach  student  weighs  or  measures  the  volume  of  50 
fresh  seeds  of  the  bean,  pea  or  Indian  corn  in  the  manner 
described  above.  Having  noted  the  weight  or  volume 
in  his  notebook,  he  pours  the  seeds,  with  the  water,  into 
one  of  his  bottles,  corks  the  latter  and  writes  his  name, 
with  the  date,  on  the  paper  pasted  on  its  side.  He  then 
repeats  the  process  with  seeds  of  the  honey  locust,  yellow 
wood  or  some  other  seed  that  does  not  readily  absorb 
cool  water,  and  after  recording  the  data  in  his  notebook, 
places  the  bottles  in  a  warm  place  until  the  following 
day,  when  he  again  determines  the  weight  or  volume  of 
the  two  kinds  of  seed.  The  seeds  placed  in  the  first  bot- 
tle will  usually  be  found  to  have  nearly  or  quite  doubled 
in  size,  while  those  in  the  second  bottle  have  scarcely 
swollen  at  all. 

Next,  show  the  class  a  sample  of  the  second  lot  of 
seeds  that  have  fully  swollen  from  soaking  in  hot  water. 
Impress  upon  their  minds  the  fact  that  while  most  seeds 
readily  absorb  moisture  at  ordinary  temperatures,  a  few 
kinds  do  not,  and  seeds  of  the  latter  class  need  to  be 
soaked  cautiously,  before  planting,  in  hot  water  (27d). 

The  rate  at  which  seeds  absorb  water  depends 

a  —  Upon  the  water  content  of  the  medium  (27).  Weigh 
3  samples  of  navy  beans.  Place  one  sample  in  water,  a 
second  in  very  damp  earth  and  the  third  in  slightly 
damp  earth.  Weigh  again  the  next  day  and  compute 
the  water  absorbed  by  the  three  lots. 

b  —  Upon  the  points  of  contact.  Weigh  2  samples  of 
navy  beans,  placing  one  sample  in  moist  soil  without 
compacting,  and  the  second  in  the  same  kind  of  soil  well 
compacted  about  the  seeds.  Determine  the  water  ab- 
sorbed by  the  two  samples  the  next  day. 

c — Upon  temperature.  Eepeat  the  above  with  2  sam- 
ples of  navy  beans,  placing  one  lot  in  a  temperature  of 
80°  to  90°  F.,  and  the  other  in  40°  to  50°  F. 

Other  means  of  using  the  apparatus  shown  in  Fig.  176 
will  occur  to  the  thoughtful  teacher.  It  may  be  used 
for  determining  specific  gravities  by  dividing  the  weight 
by  the  volume. 


272  Principles  of  Plant  Culture. 

Germination  (28).  Give  an  exercise  in  testing  seeds 
with  the  apparatus  shown  in  Fig.  6. 

Moisture  essential  to  germination  (29).  Soak  one  lot  of 
navy  beans  in  water  until  they  are  fully  swollen,  and 
another  lot  until  they  are  about  half  swollen.  Wipe  the 
beans  as  dry  as  possible,  put  each  lot  into  a  bottle,  cork 
the  bottles,  and  set  them  in  a  warm  room.  The  fully- 
swollen  beans  will  usually  germinate  promptly,  while 
the  others  will  not. 

Oxygen  essential  to  germination  (31).  Perform  the  saucer 
experiment  as  described. 

Also  place  seeds  of  rice  in  two  bottles,  and  add  to  each, 
water  that  has  been  boiled  20  minutes;  cover  the  water 
in  one  bottle  with  a  little  olive-  or  cotton- seed  oil.  It  is 
important  to  soak  the  seeds  a  short  time  in  boiled  water 
before  putting  them  in  the  bottles  to  remove  the  air  in 
contact  with  their  seed-cases. 

Germination  hastened  by  soaking  seeds  (36).  Soak  seeds 
of  Indian  corn  two  or  three  hours  in  warm  water,  and 
let  each  student  place  in  a  seed  tester  a  sample  of  the 
soaked  seeds,  with  one  or  two  other  seeds  of  the  same 
kind  that  have  not  been  soaked. 

Germination  hastened  by  mutilating  the  seed- case  (37). 
This  may  be  illustrated  with  seeds  of  the  navy  bean,  in 
the  seed  tester. 

The  plantlet  (41).  Place  seeds  of  radish,  onions  etc., 
loosely  on  the  surface  of  a  saucer  filled  with  fine  moist 
loam;  keep  the  surface  moist  and  note  the  repeated  at- 
tempts of  the  hypocotyl  to  enter  the  soil. 

Seeds  of  the  pumpkin  family  should  be  planted  flatwise  (43). 
Plant  seeds  of  the  pumpkin  or  squash,  in  the  three  posi- 
tions indicated,  in  large  greenhouse  saucers.  Cover  each 
saucer  with  a  pane  of  glass  and  place  all  in  a  warm  room 
until  the  plantlets  appear,  after  which  note  the  number 
of  each  lot  of  seeds  of  which  cotyledons  appear  above 
the  surface. 

Development  of  plantlets  (45-47).  Devote  several  exer- 
cises to  a  study  of  the  development  of  plantlets  of  the 
bean,  pea,  wheat,  Indian  corn,  pumpkin,  etc.  To  fur- 
nish the  plantlets,  seeds  of  the  different  sorts  should  be 


Appendix  —  Syllabus  of  Laboratory  Work.         273 

planted  on  several  successive  days,  beginning  at  least  10 
days  in  advance. 

Not  all  seeds  should  be  deeply  planted  (48).  Plant  seeds 
of  the  bean,  pea,  Indian  corn  and  wheat  in  6-inch  flower 
pots,  at  three  different  depths,  viz.,  ^  inch,  3  inches  and 
6  inches  from  the  bottom;  place  the  pots  in  a  warm 
place  for  3  weeks,  after  which  carefully  remove  the  soil, 
noting  the  germination  of  the  seeds  in  the  different 
layers. 

Vigor  ofplantlet  proportionate  to  size  of  seed  (49).  Plant 
large  and  small  specimens  of  navy  beans  by  themselves, 
in  greenhouse  saucers,  and  permit  them  to  germinate. 
The  smaller  seeds  usually  germinate  earlier  than  the 
larger,  but  they  produce  more  slender  plantlets,  which 
soon  fall  behind  the  others  in  development. 

Plantlet  visible  in  the  seed  (54).  Boil  samples  of  various 
kinds  of  seeds  until  they  are  fully  swollen,  after  which 
require  the  students  to  dissect  them  and  to  seek  out  the 
plantlets.  Lenses,  needles  and  forceps  are  very  useful 
in  this  work. 

The  cotyledons  a  storehouse  for  food  (60).  Eemove  the 
cotyledons  of  some  bean  plantlets  growing  in  a  flower 
pot  or  saucer,  leaving  those  of  other  plantlets  intact. 
After  a  week  note  the  result  in  the  checked  growth  of 
the  mutilated  plants. 

Vascular  bundles  (68).  Study  these  as  shown  in  the 
stalk  of  Indian  corn,  in  the  leaf  stems  of  various  plants 
and  in  the  leaf  scars  on  the  stems  of  plants. 

Cambium  layer  (69).  Locate  this  in  sections  of  various 
dicotyledonous  stems,  including  the  potato  tuber;  also 
note  the  absence  of  the  cambium  layer  in  monocotyle- 
donous  stems. 

Itoot-hairs  (101).  Study  these  as  illustrated  when  seeds 
germinate  in  the  seed  tester.  Germinated  radish- seeds, 
left  in  the  seed  tester  two  or  three  days,  usually  develop 
root-hairs  in  great  abundance.  Also  search  out  the  root- 
hairs  in  potted  plants.  Emphasize  the  difference  be- 
tween root- hairs  and  root  branches. 

Effects  of  transplanting  on  root  branching  (105).  Study 
young  plants  of  lettuce,  tomato,  cabbage  etc.,  that  have 


274  Principles  of  Plant  Culture. 

been  pricked  off,  and  compare  their  roots  with  those  of 
others  that  have  not  been  pricked  off. 

Relation  of  roots  to  food  supply  (112).  Plant  seeds  of  the 
radish  in  saucers  containing  clean  sand  and  potting  soil 
respectively,  and  when  the  seedlings  have  attained  some 
size,  wash  out  and  examine  the  toots  in  the  two  soils. 

Root  tubercles  (113).  Study  the  roots  of  young  clover 
plants  of  various  ages,  and  note  how  early  in  the  devel- 
opment of  the  plant  the  tubercles  are  discernible. 

I'ndergrouud  siems  (115).  Study  the  development  of 
the  potato  plant  from  growing  specimens,  noting  the 
points  at  which  the  tuber-bearing  stems  originate,  and 
the  marked  difference  between  these  and  the  roots. 

Nodes  and  internodes  (116).  Observe  the  nodes  in  the 
stems  of  many  plants,  noting  the  relation  of  the  diameter 
of  the  young  stem  to  the  length  of  the  internodes;  also  note 
the  undeveloped  internodes  near  the  terminus  of  the  stem. 

Buds  (128).  Study  specimens  of  leaf- buds  from  many 
plants,  noting  their  structure,  position  etc. 

Flower -buds  (133).  Study  the  form  and  location  of  the 
flower-buds  in  many  plants,  particularly  in  fruit  trees. 

Parts  of  the  flower  ( 141 ) .  Study  the  parts  of  the  flower, 
explaining  the  function  of  each  part. 

Perfect  and  imperfect  flowers  (154).  Study  these  as  pro- 
duced .by  several  different  plants,  particularly  of  the 
strawberry. 

Degree  of  maturity  necessary  to  germination  (163).  Test 
seeds  of  Indian  corn,  pea,  tomato  etc.,  that  were  gathered 
at  varying  stages  of  maturity. 

Seed  vitality  limited  by  age  (165).  Test  seeds  of  lettuce, 
parsnip,  onion  etc.,  1  year,  2  years  and  5  years  old  re- 
spectively. 

Stratification  of  seeds  (170).  Perform  the  process,  as 
described,  in  boxes  or  large  flower* pots. 

Sun-scald  (186).  Eequire  each  student  to  make  a  lath 
tree  protector  (Fig.  59). 

Winter  protection  of  plants  (202).  Protect  half-hardy 
shrubs  by  wrapping  them  with  straw  or  covering  them 
with  earth. 

Foretelling  frost  (207).  Devote  an  exercise  to  the  use  of 
the  psychrometer  and  the  computation  of  the  dew  point. 


Appendix  —  Syllabus  of  Laboratory  Work.         275- 

Plant  protectors  (279).  Require  each  student  to  make 
at  least  one  plant  protector,  as  shown  in  Fig.  67,  patterns 
for  which  are  to  be  furnished. 

Kerosene  emulsion  (294).  Let  each  student  make  a 
given  quantity  of  the  kerosene  emulsion  after  one  of  the 
formulas  given. 

Spraying  pumps  (304).  Give  at  least  one  exercise  to  the 
construction  and  use  of  spraying  pumps  and  nozzles. 

Prevention  of  grain  smuts  (325).  Require  the  students 
to  treat  a  quantity  of  oats  to  hot  water  as  described. 

Bordeaux  mixture  (329).  Require  each  student  to  make 
a  stated  quantity  of  the  Bordeaux  mixture  after  the  for- 
mula given. 

Propagation  by  seeds  (344).  Instruct  the  students  in  the 
use  of  the  hand  seed  drill  and  broadcast  sower.  Let 
them  ascertain  how  much  clover  seed  the  broadcast  ma- 
chine is  sowing  per  acre,  by  laying  on  the  ground  or 
floor  several  sheets  of  paper,  exactly  one  foot  square, 
painted  with  glycerine  to  catch  the  falling  seeds.  Hav- 
ing learned  the  average  number  of  seeds  deposited  per 
square  foot  with  a  given  rate  of  motion  of  the  machine, 
let  the  students  compute  the  number  of  seeds  sown  per 
acre,  and  reduce  this  to  ounces.  The  number  of  clover 
seeds  in  an  ounce  may  be  ascertained  by  dividing  an 
ounce  of  the  seed  among  the  students  for  counting. 

Propagation  by  layers  (349).  Instruct  the  students  in 
layering  canes  of  the  grape,  and  in  mound-layering  the 
stems  of  the  gooseberry. 

The  bulb  (352).  Dissect  bulbs  of  the  onion,  tulip,  lily, 
etc.,  ascertaining  their  structure  and  finding  the  embryo 
flowers. 

The  cold-frame  (364).  Require  the  students  to  make  a 
drawing  and  write  a  description  of  a  cold-frame,  from  a 
model  furnished  them. 

The  hotbed  (365).  Let  the  students  assist  in  making  a 
hotbed  after  the  plan  described.  Also  let  them  note  the 
temperature  of  the  soil  within  the"  frame  on  several  suc- 
cessive days  after  the  bed  is  finished,  and  give  them  in- 
struction in  ventilating  the  hotbed. 

The  propagating  bed  (368).  Require  the  students  to  make  a 
propagating  bed  in  the  greenhouse,  after  the  plan  described. 


276  Principles  of  Plant  Culture. 

Stem  cuttings  (373-375).  Let  the  students  make  cuttings 
from  the  stems  of  the  grape,  currant,  etc.,  and  plant 
them,  both  in  the  propagating  bed  and  in  the  garden. 

Root-cuttings  (376).  Give  a  lesson  in  making  root-cut- 
tings of  the  raspberry  or  blackberry,  in  packing  the 
same  for  winter  storage,  and  in  planting  them  in  the 
propagating  bed,  and  in  the  garden. 

Green  cuttings  (380-381).  Give  a  lesson  in  making  and 
planting  cuttings  of  coleus,  geranium,  rose  etc.,  followed 
by  instructions  in  the  care  of  green  cuttings  in  the  prop- 
agating bed. 

Leaf  cuttings  (382).  Give  a  lesson  in  making  and  plant- 
ing leaf  cuttings  of  the  begonia. 

Grafting  wax  etc.,  (387—389).  Give  a  lesson  in  making 
grafting  wax,  grafting  cord  and  grafting  paper,  as  de- 
scribed. 

Whip-grafting  (390-391).  Give  several  lessons  in  whip- 
grafting  including  grafting  both  of  the  stem  and  of  the  root. 

Clejt  grafting  (392).  Give  one  or  two  lessons  in  cleft 
grafting. 

Side  grafting  (393).  Give  a  lesson  in  side  grafting,  as 
described. 

Budding  (394).  Give  one  or  more  lessons  in  budding, 
.as  described.  The  bark  on  the  stocks  may  be  made  to 
peel  by  boiling,  and  trimmed  bud  sticks  may  be  pre- 
served for  winter  use,  in  dilute  alcohol. 

Approach  grafting  (399).  Give  one  exercise  in  approach 
grafting  as  described. 

Packing  plants  for  transportation  (405).  Devote  one  ex- 
ercise to  packing  strawberry,  cabbage  or  some  other 
herbaceous  plants,  as  described. 

Heeling-in,  Replanting  (408-410).  Give  one  or  more  les- 
sons in  heeling- in  and  planting  trees,  as  described;  also 
at  least  one  lesson  in  planting  root  grafts,  cuttings  and  herb- 
aceousplants  as  shown  in  Figs.  143-144;  and  a  lesson  in 
planting  strawberry  plants,  as  shown  in  Figs.  145-146. 

Potting  and  shifting  (412).  Give  two  or  more  lessons  in 
potting  and  shifting,  as  shown  in  Figs.  147-150. 

Pruning  (427  etc.).  Give  one  or  more  lessons  in  prun- 
ing by  the  methods  described. 

Cross  pollination  (441).  Give  one  or  more  lessons  in 
cross  pollination,  as  described. 


INDEX. 


The  numbers  refer  to  pages. 


Accumulation  of  reserve  food,  how 
to  promote,  91. 

Acid  phosphate,  151. 

Active  state  of  protoplasm,  15. 

Adventitious  buds,  86. 

Aeration  of  soil  promoted  by  drain- 
age, ()!». 

Air-dry  denned,  15. 

Air,  roots  require,  65,  66. 

Ammoniacal  solution  of  copper  car- 
bonate, 177. 

Ammonium  sulfate,  151. 

Animal  parasites,  154. 

Animals,  domestic,  denned,  11. 

Annular  budding,  221. 

Anther,  95. 

Apparatus  for  applying  insecti- 
cides, 164. 

Appendix,  269. 

Apple,  blight  of,  172,  254;  maggot, 
170;  scab,  174. 

Approach  grafting,  184,  212,  224. 

Army  worm,  164. 

Arsenic  compounds,  158;  are  deadly 
poisons,  159. 

Arsenic,  white,  158. 

Arsenious  acid,  158. 

Arsenite  of  copper,  158;  of  lime,  158. 

Art  and  science  denned,  9;  how  best 
learned,  10. 

Assimilation  denned,  43. 

Baldridge  transplanter,  236. 
Books  recommended  for  collateral 

reading,  114,  180,  258,  268. 
Bark  bursting,  122. 
Bark,  epidermis  replaced  by,  49. 
Bemis  transplanter,  236. 
Birds,  damage  from,  154, 155. 
Black-heart,  121. 
Black  knot  of  plum,  172,  254. 


Black  rot  of  grape,  176. 

Blanching  of  vegetables,  144. 

Blight  of  apple  and  pear,  172,  254. 

Bloom  denned,  49. 

Board  screen  for  shading  young 
plants,  141. 

Bordeaux  mixture,  175;  diseases 
prevented  by,  176. 

Borers  in  trunks  of  trees,  157, 166, 167. 

Branches,  development  of,  from  lat- 
eral leaf-buds,  85;  of  trees,  to  pre- 
vent splitting  down  in  pruning, 
244. 

Branching  stimulated  by  pinching, 
80. 

Branching  of  roots,  conditions  af- 
fecting, 73;  how  stimulated,  74. 

Breeding  denned,  17. 

Brittleness  of  plant  tissues,  59. 

Broom  rape  of  hemp  and  tobacco, 
171. 

Brush  screen  for  shading  plants,  141. 

Bud,  210,  220. 

Budding,  212,  220;  annular,  221;  ring, 
221;  shield,  221;  success  in  de- 
pendent on,  221;  T,  221. 

Budding  knife,  223. 

Buds,  84;  adventitious,  86. 

Buhach,  159. 

Bulb.  189. 

Bulbels,  189. 

Bulblets,  189. 

Bundling  trees  for  transportation, 
230. 

Cabbage  caterpillar,159;  maggot,  167; 

club-root  of,  174. 

Calcium,  part  played  by  in  plant,. 
'     45. 

Callus,  how  formed,  56. 
Calyx,  94. 

(277) 


:278 


Index. 


Cambium  layer,  52;  from  different 
plants  may  unite,  53. 

Carbon,  proportion  of  in  vegetable 
material,  44;  sources  of,  in  plants, 
42. 

•Caulicle,  33. 

Cauliflower  heads  to  be  shaded 
from  sunlight,  142. 

Caustics,  destroying  insects  by,  157- 

Cell  division,  15. 

Cells,  guard,  49;  palisade,  49;  some 
properties  of,  14. 

•Cellular  structure  of  living  beings, 
13. 

Chili  saltpeter,  150. 

Chinch  bug,  163. 

€hlorid  of  potash,  151. 

Chlorophyll  defined,  41;  forms  only 
in  light,  41 ;  iron  essential  to  form- 
ation of,  45;  no  food  formed  with- 
out, 42. 

€hlorophyll  bodies,  42. 

€ion,  210,  212. 

€ion  grafting,  212. 

Classification  defined,  17;  illustrat- 
ed, 19. 

Cleft  grafting,  216. 

Close-pollination,  100. 

Clouds  tend  to  avert  frost,  130. 

Clover,  dodder  of,  171. 

€lub-root  of  cabbage,  174. 

Codling  moth,  168. 

Cold  air  drainage,  130. 

Cold,  excessive,  how  affecting  the 
plant,  118. 

Cold-frame,  194. 

Composite  flowers,  96. 

Cond  i  tions  affecti  n  g  power  of  pi  an  ts 
to  endure  cold,  119. 

Cooling  the  plant,  immediate  effect 
of,  118. 

Copper  carbonate,  ammoniacal  so- 
lution of,  177. 

Corm,  190. 

Corn,  detasseling,  252;  smut,  172. 

Corolla,  94. 

Cotyledons  defined,  36. 

Covering  of  seeds  in  planting,  why 
important,  33. 

Cracks  in  fruits  and  vegetables  due 
to  excessive  moisture,  136. 


Crop,  affected  by  age  of  seed,  108;  a 
growing,  tends  to  conserve  fertil- 
ity, 153;  removal  of,  tends  to  re- 
duce plant  food  in  the  soil,  147; 
rotation  of,  economizes  plant 
food,  153. 

Crops,  trees  detrimental  to  neigh- 
boring, 59. 

Crossed  seedlings,  selection  of,  267. 

Crosses,  after  care  of,  266;  and  hy- 
brids defined,  20;  variability  of,  20. 

Cross  fecundation,  how  accom- 
plished, 264. 

Crossing,  selection  of  subjects  for, 
264;  variation  produced  by,  263. 

Crossings,  planting  with  reference 
to  chance,  268. 

Cross-pollination,  99;  advantage  of, 
to  plants,  100. 

Cucumber,  beetle,  156;  screen-cov- 
ered frame  for  hills  of,  156. 

Cucurbitse,  provision  in,  to  aid 
plantlet  to  emerge  from  seed- 
case,  33,  34. 

Cultivation  tends  to  prevent 
drought,  139. 

Culture,  aim  of,  11;  deals  with  life, 
12;  defined,  10;  plants  have  im- 
proved under,  259;  variation  pro- 
duced by,  262. 

Curculio,  166, 169. 

Currant  worm,  159. 

Current,  evaporation,  60;  of  pre- 
pared food,  61. 

Cuticle  defined,  49. 

Cutting  defined,  191;  essential  char- 
acters of  a,  192. 

Cuttings,  conditions  favoring 
growth  of,  193;  from  active 
plants,  205;  from  dormant  plants, 
200;  from  dormant  stems,  202;  of 
woody  plants,  preferably  made 
in  autumn,  112;  parts  of  plants  to 
be  used  for,  193;  planting  in  au- 
tumn, 202;  storage  of,  201;  tool  for 
planting,  235. 

Cuttings,  green,  205;  especial  care 
necessary  in  propagating  plants 
from,  206;  how  made  from  herba- 
ceous plants;  207;  how  made  from 


Index. 


279 


Cuttings,  woody  plants,  208;  to  be 
potted  as  soon  as  roots  are  formed, 
207. 

Cuttings  ,  leaf,  propagation  by,  208. 

Cuttings,  mallet,  203. 

Cuttings,  root,  propagation  by,  204. 

Cuttings,  stem,  202;  to  make  and 
plant,  203. 

Cutworms,  157. 

Dalmatian  insect  powder,  159. 

Damage  from  cold  prevented  by 
protecting  with  non-conducting 
material,  125. 

Dam  ping  off,  207. 

Darkening  of  wood,  121. 

Deflowering  denned,  243. 

Defruiting  denned,  243. 

Density,  pruning  for,  248. 

Depth  of  roots  in  soil,  75. 

Destruction  of  terminal  buds  by 
cold,  121. 

De-tasseling,  242,  252. 

Devices  for  transplanting,  235. 

Dew  point,  how  to  compute  the, 
129;  table  for  computing,  129. 

Dibber,  235. 

Dicotyledons  defined,  36. 

Diffusion,  law  of,  47. 

Dioecious  flowers,  100. 

Disbudding  defined,  242;  trees,  248. 

Disease  defined,  13. 

Distal  defined,  79. 

Dodder  of  clover  and  flax,  171. 

Domestic  plants  and  animals  de- 
fined, 11. 

Dormant  state  of  protoplasm,  15. 

Drainage  promotes  soil  aeration,  69; 
required  by  potted  plants,  69. 

Dressing  defined,  242. 

Drought  causes  toughness  of  plant 
tissue,  138;  cultivation  a  prevent- 
ive of,  139;  mulching  a  preventive 
of,  139;  tends  to  hasten  maturity, 
128. 

Drying  kills  plant  tissues,  140. 

Duration  of  germinating  power,  105; 
of  seed  vitality,  conditions  affect- 
ing, 106. 

Electric  light,  use  of,  in  glass 
houses,  143. 


Elements  essential  in  plant  food, 
44;  part  played  by  different,  44. 

Emasculation  of  flowers,  264. 

Embryo  defined,  40. 

Endosperm  defined,  40. 

Environment  defined,  10;  factors  of, 
115. 

Epidermis  defined,  48;  replaced  by 
bark  in  older  stems. 

Evaporation  current,  60. 

Evergreen  trees  destroyed  by  un- 
timely warm  weather  in  spring, 
116. 

Evolution,  theory  of,  21. 

Factors  of  environment,  115. 

Families,  how  formed,  18. 

Farm  manure,  152. 

Fecundation,  98;  cross,  how  accom- 
plished, 264. 

Feebleness  defined,  12. 

Ferns,  how  grown  from  spores,  39. 

Fertilization,  98. 

Fertilizer  requirements  of  crops,152. 

Filament,  95. 

Fir  tree  oil,  163. 

Fibro-vascular  bundles,  51. 

Fixing  desirable  variations,  260. 

Flax,  dodder  of,  171. 

Flea  beetles,  161. 

Flower,  93;  certain  parts  of,  often 
wanting,  96;  parts  of  the,  93;  parts 
of,  vary  in  form  in  different  spe- 
cies, 96. 

Flower-buds,  86;  conditions  affect- 
ing formation  of,  89;  destroyed  by 
cold,  123;  how  distinguished  from 
leaf  buds,  87;  ringing  often  causes 
formation  of,  92,  253. 

Flowering  and  fruiting,  root  prun- 
ing to  promote,  253. 

Flowering,  glumes,  97. 

Flowering,pinching  to  promote,252. 

Flowers,  composite,  96;  especially 
sensitive  to  cold,  123;  of  the  grass 
family,  97;  tend  to  exhaust  the 
plant,  93. 

Flowers  and  fruit,  obstructing 
growth  current  to  promote,  253; 
pruning  for,  252. 

Flow  of  sap  in  spring,  60. 


280 


Index. 


Food,  current  of  prepared,  61;  ele- 
ments of,  most  likely  to  be  defi- 
cient in  the  soil,  45;  insufficient, 
dwarfs  the  plant,  147;  materials 
of,  how  distributed  through  plant, 
46;  reserve,  15;  storage  of  reserve, 
63;  use  of  reserve,  63. 

Food  preparation  the  function  of 
leaves,  81. 

Food  supply,  relation  of  roots* to, 
77;  unfavorable,  effect  of,  011 
plant,  146. 

Formative  pruning,  245. 

Formula  for  Bordeaux  mixture,  175. 

Formulas  for  kerosene  emulsion, 
161;  for  resin  washes,  162. 

Freezing  of  plants  favored  by  much 
water  in  plant  tissue,  118. 

Freezing,  severe,  may  split  open 
tree  trunks,  122. 

Frost,  conditions  that  tend  to  avert, 
130;  how  foretold,  127;  plants  in- 
jured by,  how  saved  from  serious 
damage,  120;  liability  to,  depend- 
ing comparatively  little  upon  lat- 
itude, 131;  localities  most  subject 
to,  131;  methods  of  preventing  in- 
jury by,  132. 

Frozen  tissues,  treatment  of,  120. 

Fruit,  101;  or  flowers,  pruning  for, 
252;  thinning  of,  103,  252. 

Fruitfulness  promoted  by  restrict- 
ing growth  current,  63. 

Fruiting,  obstructing  growth  cur- 
rent to  promote,  253;  root  pruning 
to  promote,  253. 

Fruits  and  vegetables,  cracks  in, 
caused  by  excessive  moisture,  136; 
rarely  develop  without  fecunda- 
tion, 102;  ripening  of,  103. 

Fungi,  171;  endophytic,  173;  epi- 
phytic, 178;  methods  of  controll- 
ing, 172. 

Fungicides,  172;  various,  175,  177. 

Fungous  diseases,  need  of  consult- 
ing specialists  in,  178. 

Gathering  and  storing  of  seeds,  104. 
Genera,  how  formed,  18. 
Generic  name  defined,  20. 
Genus,  how  formed,  18. 
Germinating  power,duration  of,106. 


Germination  defined,  24;  dependent 
on  stage  of  maturity  of  seeds,  104; 
hastened  by  compacting  soil,  28; 
hastened  by  mutilating  seed-case, 
30;  hastened  by  soaking  seeds,  29; 
in  water,  27;  moisture  essential 
to,  25;  not  hindered  by  light,  32; 
oxygen  essential  to,  26;  prompt- 
ness in,  important,  28;  requisites 
for,  28;  retarded  by  excess  of 
water,  29;  seed-case  in,  33;  temper- 
ature at  which,  takes  place,  26; 
time  required  for,  32;  warmth  es- 
sential to,  25;  when  completed,  25. 

Germinations,  earlier,  form  more 
vigorous  plantlets,  38. 

Girdling,  killing  trees  by,  62. 

Glumes,  97. 

Gooseberry  mildew,  176. 

Gophers,  damage  from,  155. 

Gormands  on  fruit  trees,  135. 

Graft,  210. 

Grafting,  approach,  212,  224;  cion, 
212;  cleft,  216,  218;  cord,  214;  herba- 
ceous, 200,  219;  how  possible,  53; 
objects  of,  210;  paper,  214;  plants 
uniting  by,  211;  propagation  by, 
209;  root,  215;  side,  219;  top,  215; 
veneer,  219;  wax,  how  made,  212; 
whip,  214. 

Grafts,  whole  root,  216. 

Graminese,  flowers  of,  97. 

Grape  mildew,  175. 

Grass  family,  flowers  of,  97. 

Grasshoppers,  164. 

Greenhouse,  197;  heating  devices 
for,  198. 

Growing  point  defined,  50. 

Growth  by  cell  division,  15;  cutting 
back  new,  to  promote  flowering, 
252;  decline  of,  109;  defined,  15;  in 
diameter,  of  stems,  54;  of  roots  in 
length,  70;  pruning  for,  251;  re- 
tarded by  insufficient  moisture  in 
soil,  138;  tardy  starting  of,  after 
transplanting,  240;  water  neces- 
sary to,  45. 

Growth  current,  obstructing,  to  pro- 
mote flowering  and  fruiting,  253; 
restriction  of,  promotes  fruitful- 
ness,  63. 

Guard  cells,  49,  50. 


Index. 


281 


Hardiness,  defined,  1:5;  dependent 
on  degree  of  dormancy,  111. 

Healing  of  wounds,  55. 

Health  defined,  13. 

Heat,  excessive,  how  affecting 
plants,  115. 

Hedge  shears,  257. 

Heeling-in  plants,  231. 

Hellebore  powder,  159, 160. 

Hemp,  broom  rape  of,  171. 

Herbaceous  grafting,  200,  219. 

Herbaceous  stems  defined,  53. 

Heredity  and  variation,  16. 

Hermaphrodite  flowers,  100. 

Hoarfrost,  cause  of,  126. 

Horizontal  extent  of  roots,  75. 

Host  (of  parasites)  defined,  21. 

Hotbed,  the,  195. 

Hotbeds  require  care  in  ventilation, 
69. 

Hot  water,for  destroying  insects,163; 
t  reatment  for  grain  smut,  173. 

Humidity,  methods  of  controlling, 
200. 

Hybrids  and  crosses  defined,  20. 

Hydrocyanic  gas,  162. 

Hydrogen,  source  of,  in  plants,  44. 

Hyphfe,  172. 

Hypocotyl,  defined,  32;  develops  dif- 
ferently in  different  species.  36; 
roots  start  from,  35;  seeds  in  which 
it  lengthens  must  be  planted  shal- 
low, 36. 

Ice  often  destroys  low  plants,  124. 

Immature  vs.  ripe  seeds,  105. 

Imperfect  flowers,  100. 

Implements,  for  pruning,  255;  for 
t  transplanting,  235,  236,  237. 

Improvement  possible  through 
plant  variability,  260. 

Individuals  defined,  18. 

Injury  by  cold,  methods  of  avert- 
ing, 124. 

Insecticides,  157;  apparatus  for  ap- 
plying, 164;  use  of,  165. 

Insects,  beneficial,  156;  burrowing, 
1<>7;  destroying  by  poisons  or  caus- 
tics, 157;  eat  ing- insects,  166;  hand- 
picking,  157;  injurious,  life  history 
of,  170;  leaf-eating,  166;  ravages, 
17 


Insects,  method  of  preventing,  156; 
repelling,  by  means  of  offensive 
odors,  157;  root-eating,  166,  167; 
sucking,  166,  170. 

Insects,  trapping,  156. 

Internodes,defliied,  78;  stem  length- 
ens by  elongation  of,  79;  ultimate 
length  of,  80. 

Iron  essential  to  formation  of 
chlorophyll,  45. 

Irrigation,  139. 

Kainit,  152. 

Kerosene,  applied  with  water,  161; 
as  an  insecticide,  161;  emulsion, 
161. 

Killing  trees  by  girdling,  62. 

Knife,  budding,  223;  grafting,  213; 
pruning,  255. 

Knowledge,  application  of,  essen- 
tial to  success,  9. 

Lath  screen  for  shading  plants,  140. 

Leaf-buds,  86;  comparative  vigor 
of,  89. 

Leaf  cuttings,  propagation  by,  208. 

Leaf  development,importance  of,81. 

Leaf  fall,  time  of,  an  index  of  wood 
maturity,  111. 

Leaf-eating  insects,  166. 

Leaf  miners,  167,  168. 

Leaves,  81;  are  usually  short-lived, 
83;  comparative  size  of,  83;  func- 
tion of,  81;  manurial  value  of,  84. 

Leguminous  plants  enrich  the  soil 
with  nitrogen,  77, 150. 

Lenticels,  50. 

Lever  shears,  257. 

Life,  culture  deals  with,  12. 

Life,  what  is  it?  12. 

Lifting  large  trees,  227. 

Lifting  the  plant,  directions  for,  227. 

Light  does  not  hinder  germination, 
32. 

Light,  unfavorable,  how  affecting 
the  plant,  140. 

Living  beings,  cellular  structure  of, 
13. 

Localities  most  subject  to  untimely 
frosts,  131. 

Locusts,  164. 


282 


Index. 


London  purple,  158. 
Low  plants  often  destroyed  by  ice, 
124. 

Magnesium,  part  played  by,  in 
plftnt,  45. 

Mallet  cuttings,  203. 

Manure  increases  water-holding 
capacity  of  soil,  45. 

Maiiurial  value  of  leaves,  84. 

Maturative  pruning,  255. 

Maturity  of  plants,  influence  of 
drought  on,  138. 

Maximum  defined,  25. 

Mealy  bug,  163. 

Melons,  screen-covered  frame  for 
protecting  hills  of,  1-56. 

Mice,  damage  from,  154. 

Minimum  defined,  25. 

Moisture,  an  enemy  to  stored  seeds, 
107;  essential  to  germination,  25; 
excessive,  causing  cracks  in  fruits 
and  vegetables,  136;  excites  root 
growth,  65;  excessive,  in  air  in- 
jurious to  plants,  137;  insufficient, 
in  air  causing  excessive  trans- 
piration, 137;  insufficient,  in  soil 
retards  growth,  138. 

Monocotyledones  defined,  36. 

Monoecious  flowers,  100. 

Mound-layering,  187. 

Mulching,tends  to  prevent  drought, 
139;  transplanted  stock,  239. 

Muriate  of  potash,  151. 

Names,  scientific,  why  used,  19. 

Nitrates  in  the  soil,  sources  of,  149. 

Nitrification,  149, 150. 

Nitrogen,  148, 150;  in  protoplasm,  44; 
in  rain  and  snow,  150;  sources  of, 
in  plant,  44;  stimulates  growth, 
146. 

Nodes  defined,  78. 

Northerly  exposure  least  trying  to 
plants  in  winter,  125. 

Notching,  243,  254. 

Nursery  trees  benefitted  by  trans- 
planting, 75. 

Objects  of  grafting,  210;  of  pruning, 
245. 


Oedemn  in  plants,  caused  by  ex- 
cessive watering,  135. 

Onion  mildew,  174. 

Optimum  defined,  25. 

Orange  rust,  172. 

Organic  manures,  partially  decom- 
posed, act  more  promptly  than 
fresh  ones,  150. 

Organic  matter,  importance  of,  in 
soil,  68. 

Osmosis  defined,  60. 

Ovary,  95. 

Overbearing  should  be  prevented, 
103. 
Ovule,  95. 

Oxygen,  essential  to  germination, 
26;  necessary  to  life  of  roots,  65; 
source  of,  in  plants,  44. 

Oyster-shell  bark-louse,  161. 

Packing  plants  for  transportation, 
229. 

Pales,  97. 

Palets,  97. 

Palisade  cells,  49. 

Parasites,  animal,  154;  defined,  21; 
flowering  or  phanerogamic,  171; 
fungous,  171;  injurious,  154;  vege- 
table, 170. 

Parenchyma,  51. 

Paris  green,  158. 

Pear,  blight  of,  172,  254. 

Peeling  the  stems  of  trees,  56,  254. 

Perfect  flowers,  100. 

Persian  insect  powder,  159. 

Petals,  94. 

Phosphorus,  151;  part  played  by,  in 
plants,  45. 

Picturesqueness,  pruning  for,  247. 

Pinching  defined,  242;  stimulates 
branching,  80;  to  promote  flower- 
ing. 252 

Pistil,  95. 

Pith,  52. 

Plant  food,  elements  in,  44;  ele- 
ments of,  likely  to  be  deficient,  45; 
from  soil  must  be  dissolved  by 
soil  water,  44;  in  soil,  reduced  by 
crop  growing,  147;  sources  of,  43. 

Plant  improvement,  how  explain- 
ed, 259. 


Index. 


283 


Planting,  too  close,  causes  deficient 
light,  143;  trees,  directions  for, 
281,285;  with  reference  to  chance 
crossings,  268;  with  reference  to 
pollination,  101. 

Plantlet,  inner  structure  of,  48;  may 
need  help  to  burst  seed-case,  34; 
principal  parts  of,  41;  vigor  of, 
proportionate  to  size  of  seed,  38; 
visible  in  seed,  40. 

Plant  life,  round  of,  22,  113. 

Plant  manipulation,  181;  propaga- 
tion, 181. 

Plant,  directions  for  lifting  the,  227; 
removing  the,  229. 

Plant  tissues,  brittleness  of,  59; 
killed  by  drying,  140;  toughness 
of,  caused  by  drought,  138. 

Plants,  abnormal  development  of 
due  to  insufficient  light,  142;  af- 
fected by  unfavorable  environ- 
ment, 115;  difference  in  water  re- 
quirements of,  134;  distance  apart 
for  growing,  82;  domestic,  defined, 
11;  have  improved  under  culture, 
259;  heeling-in,  231;  injured  by  ex- 
cessive water,  133;  affected  by  par- 
asites, 153;  only  can  prepare  food 
from  mineral  substances,  43;  pack- 
ing for  transportation,  229;  potted, 
require  drainage,  69;  potting  and 
shifting,  236;  power  of,  to  endure 
cold,  119;  preparation  of,  for  re- 
planting, 231;  rapid-growing,  re- 
quire much  water,  134;  shading 
after  transplanting,  140;  those  who 
improve,  are  true  benefactors,  268. 

Plants  under  glass  liable  to  suffer 
from  deficient  light,  143;  need  of 
rest  of,  111:  not  to  be  sprinkled  in 
bright  sunshine,  116;  plants,  un- 
packing, 231;  variability  of,  260; 
washing  the  roots  of  puddled,  231; 
watering  of  potted,  69,  133,  134; 
watering  the  roots  of  recently 
transplanted,  240;  screens  for 
shading,  140,  141, 

Plum,  black  knot  of,  172,  254. 

Plum  curculio,  166,  169. 

Plumule,  41. 

Poisons,  destroying  insects  by,  157. 


Pollen,  95;  appearance  of  mature, 
265;  applying,  266;  to  prevent  ac- 
cess of  undesired,  265. 

Pole  shears,  257. 

Pollination,  98;  in  many  plants  de- 
pendent on  wind,  145;  planting 
with  reference  to,  101;  to  prevent 
self-,  264;  when  should  it  be  per- 
formed, 266. 

Potash,  caustic,  161. 

Potassium,  151;  assists  in  food 
preparation,  45;  -sulfid  solution, 
177. 

Potato,  beetle,  157, 159;  blight  of,  176; 
foliage  of,injured  by  sun  heat,  118. 

Potatoes,  knobby,  136. 

Potted  plants  require  drainage,  69; 
watering  of,  69, 133.  134. 

Potting,  and  shifting,  236;  soil,  237. 

Powdery  mildews,  178. 

Preparation  of  plants  for  replant- 
ing, 231. 

Prepared  food,  current  of,  61. 

Pricking  off  seedlings,  75. 

Principle  of  selection,  17,  259. 

Propagating  bed,  the,  199. 

Propagation  by  cuttings,  191;  by  de- 
tached parts,  184;  by  division,  181, 
183;  by  division  of  the  crown,  188; 
by  grafting,  209;  by  layers,  186; 
by  parts  intact,  181;  by  sections  of 
the  plant,  188,  191;  by  seeds,  182; 
by  specialized  buds,188;by  stolons, 
185;  by  suckers,  184;  methods  of, 
181. 

Prosenchyma,  51. 

Protective  pruning,  254. 

Protoplasm,  active  state  of,  15;  dor- 
mant state  of,  15;  some  properties 
of,  15. 

Proximal  defined,  79. 

Pruning,  defined,  242;  for  density, 
248;  for  flowers  or  fruit,  252;  for 
growth,  251;  for  picturesqueness, 
247;  for  slenderness,  247;  forstock- 
iness,  247;  for  strength,  248;  for 
symmetry,  245;  formative,  245;  im- 
plements, 255;  insufficient,  pre- 
vents formation  of  fruit  buds,  144; 
-knife,  255;  maturative,255;  objects 
of,  245;  protective,  254;  -saw,  256; 


284 


Index. 


Pruning,  season  for,  243;  -shears,  256; 
stimulative,  251;  where  and  how 
to  make  the  cut  in,  243. 

Psychrometer,  sling,  128. 

Puddled  plants,  washing  roots  of, 
231. 

Puddled  soil  denned,  26;  prevents 
germination,  27. 

Puddling  the  roots  of  trees,  230. 

Pumpkin,  provision  in,toaid  plant- 
let  to  emerge  from  seed-case,33,34. 

Pyrethrum  powder,  159. 

Rabbits,  damage  from,  155. 

Radicle,  33. 

Raspberry  pruning  hook,  257. 

Rate  of  root  growth,  76. 

Reduced  vigor,  tendencies  of,  13. 

Reducing  the  tops  of  trees  prior  to 
planting,  232. 

Removing  the  plant,  229. 

Reproduction  defined,  16;  relation 
to  growth,  16;  sexual  and  non- 
sexual,  16. 

Reserve  food,  15;  how  plants  use,  63; 
how  to  promote  accumulation  of, 
91;  storage  of,  63. 

Resin  washes,  162. 

Rest  period,  109;  not  peculiar  to 
temperate  zones,  110;  plant  pro- 
cesses may  not  entirely  cease  dur- 
ing, 112. 

Reversion,  260. 

Richards'  transplanting  tools,  236. 

Ring-budding,  221,  224. 

Ringing,  defined,  243;  often  causes 
formation  of  flower-buds,  92. 

Ripening  of  fruits,  103. 

Root,  and  the  soil,  64;  office  of,  64; 
originates  in  stem,  64;  starvation, 
62. 

Root  branching,  conditions  affect- 
ing, 73. 

Root  branching,  how  stimulated, 
74;  should  be  encouraged,  73. 

Root  cap,  70. 

Root  cuttings,  204. 

Root  grafting,  215. 

Root  grafts,  tool  for  planting,  235. 

Root  growth,  excited  by  moisture, 
65;  rate  of,  76. 


Root-hairs  absorb  water  with  con- 
siderable force,  72;  apply  them- 
selves to  soil  particles,  67,  70;  dis- 
solve soil  particles,  72;  nature  of, 
49, 70;  show  need  of  roots  for  air,  66. 

Root-killing  of  trees,  123. 

Root  pruning  to  promote  flowering 
and  fruiting,  253;  stimulates  root 
branching,  74,  75. 

Root  tubercles,  77. 

Roots,  depths  of,  in  soil,75;  destroy- 
ed by  excessive  water  in  soil,  133; 
growth  of  in  length,  70;  horizon- 
tal extent  of,  75;  of  trees,  pud- 
dling, 230;  only  youngest  active  in 
absorption,  72;  oxygen  necessary 
to  life  of,  65;  properly  and  -im- 
properly planted,  234;  relation  of, 
to  food  supply,  77;  replanting  the, 
233;  start  from  hypocotyl,  35; 
trimming  of,  prior  to  planting, 
232;  washing,  of  puddled  plants, 
231;  wetting  prior  to  planting,  233. 

Root-tip,  how  penetrates  the  soil,  69. 

Root-tips,  formation  of  should  be 
encouraged,  72. 

Rose  beetle,  157. 

Rosin  washes,  162. 

Round  of  plant  life,  the,  22,  113. 

Rust  of  blackberry,  172. 

Sacking  the  roots  of  trees,  22S. 

Saltpeter,  152. 

Sap  defined,  46. 

Sap,  flow  of  in  spring,  60. 

Sap-sprouts  on  fruit  trees,  135. 

Saw,  pruning,  256. 

Science  and  art  defined,  9;  how  best 
learned,  10. 

Scientific  names,  why  used,  19. 

Scion,  210. 

Screens  for  shading  plants,  140, 141. 

Season  for  pruning,  243. 

Seed,  102;  age  of,  as  affecting  the  re- 
sulting crop,  108;  maturing  of,  in- 
jures fodder  crops,  103;  plantlet 
visible  in,  40;  production  of  ex- 
hausts plants,  102;  selection,  im- 
portance of,  262;  vigor  of  plantlet 
proportionate  to  size  of,  38;  vital- 
ity, conditions  affecting  duration 
of,  106. 


Index. 


285 


Seed-case  defined,  23;  influence  of 
on  absorption  of  water  by  seeds, 
23;  in  germination,  33;  is  useless 
after  germination  commences,  33; 
plantlet  may  need  help  to  burst, 
34. 

Seeding,  prevention  of,  prolongs  the 
life  of  plants,  102. 

Seed-leaves  denned,  36. 

Seedlings,  pricking  off  young,  75; 
selection  of  crossed,  267;  variation 
produced  by  growing,  262;  young, 
injured  by  unobstructed  rays  of 
sun,  140. 

Seeds  absorb  water  by  contact,  22; 
a  few  germinate  in  water,  27;  dry- 
ing of,  how  affecting  their  vital- 
ity, 108;  earlier  germinating,  form 
more  vigorous  plantlets,  38;  gath- 
ering and  storing  of,  104;  germina- 
tion hastened  by  mutilating  seed- 
case,  30;  how  deep  should  they  be 
planted?  38,  183;  immature  vs. 
ripe,  105;  in  which  hypocotyl 
lengthens  must  be  planted  shal- 
low, 36;  of  pumpkin  family 
should  be  planted  flatwise,  34;  rate 
at  which  they  absorb  water,  22; 
should  be  tested  before  planting, 
31;  should  riot  be  planted  until 
soil  becomes  warm,  29;  stored, 
moisture  an  enemy  to,  107;  strati- 
fication of,  108;  very  small,  should 
not  be  covered,  39, 183;  vitality  of, 
limited  by  age,  105;  why  cover,  at 
planting,  33;  why  they  fail  to  ger- 
minate, 30;  testing,  directions  for 
31;  -tester  described,  31. 

Selection  a  means  of  fixing  varia- 
tions, 261;  of  crossed  seedlings, 
267;  of  seed,  importance  of,  262; 
of  subjects  for  crossing,  264;  prin- 
ciple of,  17,  25!). 

Self  pollination,  100. 

Sepal,  94. 

Sexual  reproduction,  16. 

Shading  plants  after  transplanting, 
240. 

Shears,  hedge,  257;  lever,  257;  pole, 
257;  pruning,  256. 

Shed  screen  for  shading  plants,  141. 


Shield  budding,  221. 

Shifting  plants,  238. 

Side  grafting,  219. 

Sifting  box  for  applying  insecticide 
powders,  164. 

Slenderness,  pruning  for,  247. 

Slips,  205. 

Slugs,  155. 

Smut  of  the  small  grains,  173;  of 
corn,  172;  of  onion,  174. 

Snails,  155. 

Sodium  nitrate,  150. 

Soil,  and  the  root,  64;  a  scene  of  con- 
stant changes,  67;  compacting, 
about  seeds  hastens  germination, 
28;  compacting  wet,  may  prevent 
germination,  27;  depth  of  roots  in, 
75;  how  penetrated  by  root-tip,  69; 
ideal,  for  land  plants,  67;  import- 
ance of  organic  matter  in,  68; 
needs  ventilation,  68;  particles  of, 
dissolved  by  rootrhairs,  71;  for 
potting,  237;  puddled,  defined,  26; 
puddled,  prevents  germination,27. 

Soil -aeration  promoted  by  drain- 
age, 69;  promotes  soil  fertility,  149. 

Species,  18. 

Specific  names  defined,  20. 

Spikelet,  97. 

Splice  grafting,  214. 

Spli  tting  down,  to  prevent  branches 
from,  251. 

Spore  germination  favored  by 
moisture,  177;  prevention  of,  173. 

Spores  defined,  39;  non-sexual,  16; 
of  ferns,  how  planted,  39. 

Spraying  outfit,  steam,  166. 

Spray  pump,  165. 

Sprinkling  of  plants  under  glass  to 
be  avoided  in  bright  sunshine,  116. 

Squash,  provision  in,  to  aid  plant- 
let  to  emerge  from  seed-case,  33; 
bug,  166;  -vine  borer,  157. 

Stable  manure,  152. 

Staking  trees  to  prevent  shaking  by 
the  wind,  234. 

Stamens,  95. 

Starvation  of  roots,  62. 

Stem  and  root  development  de- 
pendent on  number  of  leaves,  82. 

Stem  defined,  78. 


286 


Index. 


Stem,  fastest  elongation  of,  80;  how 
lengthens,  79;  root  originates  in, 
64;  vital  part  of  woody,  55. 

Stem  cuttings,  202;  how  planted, 
203;  proper  length  of,  203. 

Stems,  how  they  increase  in  diame- 
ter, 54;  underground,  78. 

Stigma,  95. 

Stimulative  pruning,  251. 

Stocks  for  grafting,  210. 

Stockiness,  pruning  for,  247. 

Stoma  defined,  49. 

Stomata  defined,  49. 

Storage  of  cuttings,  201;  of  reserve 
food,  63. 

Stratification  of  seeds,  108. 

Strawberry,  periect  and  imperfect 
flowers  of,  101. 

Strength,  pruning  for,  248. 

Striped  cucumber  beetle,  156. 

Subjects  for  crossing,  selection  of, 
264. 

Style,  95. 

Suckering  defined,  242. 

Sulfate  of  potash,  151. 

Sulfur,  part  played  by  in  plants,  45. 

Sun  heat  injurious  to  young  seed- 
lings, 140. 

Sun-scald,  117. 

Superphosphate,  151. 

Symbiosis,  149. 

Table  for  computing  dew  point,  129; 
showing  duration  of  seed  vital- 
ity, 106;  showing  germinating 
temperatures  of  seeds,  26. 

Tarred-paper  cards,  tool  for  cutting, 
168. 

T-b  udding,  221. 

Temperature  as  affecting  plant 
growth,  115;  fatal  to  protoplasm, 
116;  influence  of  on  absorption  of 
water  by  seeds,  23;  methods  of 
controlling,  194. 

Tenderness  defined,  13. 

Terminal  buds,  pinching  of,  effect 
on  wood  maturity,  124;  destruc- 
tion of,  by  cold,  121. 

Theory  of  evolution,  21. 

Thermal  belts,  131. 

Thinning  fruit,  103,  252. 


Time,  most  favorable  for  trans 
planting,  226. 

Tobacco,  broom  rape  of,  171;  decoc- 
tion of,  for  destroying  aphidse,  161; 
smoke  for  destroying  insects,  160; 
fluid  extract  of,  160;  topping,  242, 
251,  255;  -worm,  157;  frenching,  135. 

Tomato  worm,  157. 

Tongue  grafting,  214. 

Tool  for  injecting  poisonous  liquids, 
167;  for  cutting  paper  cards,  168. 

Top  grafting,  215. 

Topping,  defined,  212;  tobacco,  251, 
255. 

Transpiration,  amount  of,  58;  con- 
ditions affecting,  57;  current,  60; 
defined,  57;  excessive,  58;  exces- 
sive, caused  by  insufficient  moist- 
ure  in  the  air,  137;  increases  with 
degree  of  heat,  115. 

Transplanted  plants,  shading,  240; 
watering,  240. 

Transplanted  stock,  tardy  starting 
of,  240. 

Transplanter,  Baldridge,  236;  Bemis, 
236. 

Transplanting,  225;  benefits  nursery 
trees,  75;  endured  best  by  vigor- 
ous plants,  226;  most  favorable 
time  for,  226;  stimulates  root 
branching,  74;  devices  for,  235. 

Transplanting  tools,  Richards',  236. 

Trapping  insects,  15(5. 

Tree  trunks  split  open  by  severe 
freezing,  122. 

Trees,  bundling  for  transportation, 
230;  detrimental  to  neighboring 
crops,  59;  directions  for  planting, 
233;  killing  by  girdling,  62;  lifted 
or  lowered  to  accommodate  grad- 
ing, 228;  lifting  large,  227;  nursery, 
benefitted  by  transplanting,  75; 
puddling  roots  of,  230;  reducing 
top  of,  prior  to  planting,  232,  sack- 
ing roots  of,  228;  staking,  to  pre- 
vent shaking  by  wind,  231. 

Trimming  defined,  242;  roots  prior 
to  planting,  232. 

Tuber,  the,  190. 

Tubercles  on  roots,  77. 

Turn  of  the  year,  113. 


Index. 


287 


Underground  stems,  78. 

Unhealed  wounds  introduce  decay, 

245. 

Unisexual  flowers,  100. 
l'n packing  plants,  281. 

Variability  of  offspring  of  crosses 
and  hybrids,  20;  of  plan  Is,  2(H). 

Variation,  and  heredity,  16;  how 
can  we  produce,  202;  may  take 
place  in  any  direction,  17;  pro- 
duced by  crossing,  263;  produced 
by  culture,  2(52;  produced  by  grow- 
ing seedlings,  262. 

Variations,  how  to  fix  desirable,  260; 
not  always  permanent,  260. 

Varieties,  18;  origin  of  cultivated, 
259. 

Vascular  bundles  defined,  51. 

Vegetables,  cracks  in,  caused  by 
excessive  moisture,  186. 

Ventilation,  hotbeds  require  care 
in,  69;  soil  needs,  <>S. 

Veneer  grafting,  219. 

Vigor  defined,  12;  of  plantlet  pro- 
portionate to  size  of  seed,  38;  ten- 
dencies of  reduced,  18. 

Vital  part  of  woody  steins,  55. 

Warmth  essential  to  germination, 
25. 

Washing  the  roots  of  puddled 
plants,  281. 

Water,  adequate  supply  of  most 
important,  45;  excess  of,  retards 
germination,  29;  excessive  in  soil 
destroys  roots,  133;  force  causing 
to  rise  in  stems,  60;  insufficient, 
how  affecting  plants.  187;  manur- 
ing increases  capacity  of  soil  for, 
45;  of  plants  almost  wholly  ab- 
sorbed by  root-hairs,  46;  only 


Water— 

youngest  roots  absorb,  72;  plants 
contain  large  amounts  of,  57; 
root-hairs  absorb,  with  force,  72; 
seeds  absorb,  by  contact,  22. 

Water-sprouts  on  fruit  trees,  135. 

Water  supply,  unfavorable,  the 
plant  as  affected  by,  133. 

Watering,  excessive,  may  produce 
a  dropsical  condition,  185;  copious, 
at  intervals  preferable  to  frequent 
slight  watering,  134;  injudicious, 
133;  of  potted  plants,  69;  recently- 
transplanted  plants,  240. 

Weeds,  178;  annual,  biennial  and 
perennial,  179;  cause  deficient 
light  in  low-growing  crops,  143; 
how  destroyed,  63;  plants  as  af- 
fected by,  178 

Wet-bulb  depression,  129. 

Whip-grafting,  214. 

White  grubs,  157. 

White  hellebore,  159. 

Whole-root  grafts,  216. 

Wind  breaks,  126. 

Wind,excessive,effectof,  on  plants, 
144;  insufficient,  effect  on  the 
plant,  145;  insufficient,  promotes 
damage  from  frost,  145:  insuffi- 
,  '  cient,  promotes  development  of 
fungous  parasites,  145;  tends  to 
avert  frost,  180;  unfavorable,  how 
affecting  the  plant,  144. 

Wood  ashes,  152. 

Woodchucks,  damage  from,  155. 

Wood,  darkening  of,  121. 

Wood,  maturity  of,  favored  by  a 
dry  soil,  124;  by  pinching  termi- 
nal buds,  124;  indicated  by  leaf 
fall,  111. 

Wounds,  healing  of,  55;  unhealed, 
introduce  decay,  245. 


FIG.  177.    Students  treating  oats  to  prevent  smut,  in  the  "  garden  house  "  of  the 
University  of  Wisconsin. 


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